McMaster-Carr logo
    Enter e-mail addresses in the fields below
    Message
    Cancel
    Comments
    E-mail address (if you would like a response)
    208 Products

    Cap Nuts

    Conceal and protect protruding screw threads while fastening parts together. These nuts help prevent damage to surrounding materials and reduce injuries. Also known as acorn nuts, they have a smooth, rounded head that creates a finished look.
    Stainless Steel
    Image of Product. Front orientation. Cap Nuts. Cap Nuts.
    18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.
    Black-Oxide 18-8 Stainless Steel—Typically chosen for their appearance, these nuts have a dark, matte coating. They resist rust in wet and outdoor environments but won't hold up to the harsh chemicals that 316 stainless steel can.
    Super-Corrosion-Resistant 316 Stainless Steel—Our most corrosion-resistant cap nuts, these hold up in just about any environment. They won't degrade from exposure to weather, salt water, and most chemicals.
    Thread Size
    Thread
    Dp.
    Wd.
    Ht.
    Specs.
    Met
    Pkg.
    Qty.
    Pkg.
    18-8 Stainless Steel
    0-80
    1/16"3/16"3/16"100000000000000
    1-72
    1/16"3/16"3/16"10000000000000
    2-56
    5/64"3/16"3/16"10000000000000
    3-48
    5/64"1/4"1/4"10000000000000
    4-40
    5/32"1/4"1/4"100000000000000
    4-48
    5/32"1/4"1/4"1000000000000000
    5-40
    1/8"5/16"11/32"10000000000000
    6-32
    5/32"5/16"11/32"100000000000000
    6-32
    3/16"5/16"9/32"100000000000000
    6-40
    5/32"5/16"11/32"1000000000000000
    8-32
    5/32"5/16"11/32"100000000000000
    8-32
    3/16"5/16"9/32"100000000000000
    8-36
    5/32"5/16"11/32"1000000000000000
    10-24
    3/16"3/8"13/32"100000000000000
    10-24
    7/32"3/8"11/32"1000000000000000
    10-32
    3/16"3/8"13/32"100000000000000
    10-32
    7/32"3/8"11/32"1000000000000000
    12-24
    7/32"3/8"13/32"100000000000000
    12-28
    7/32"3/8"13/32"10000000000000
    1/4"-20
    7/32"7/16"3/8"1000000000000000
    1/4"-20
    1/4"7/16"15/32"1000000000000000
    1/4"-20
    5/16"7/16"19/32"1000000000000000
    1/4"-28
    7/32"7/16"3/8"1000000000000000
    1/4"-28
    1/4"7/16"15/32"1000000000000000
    5/16"-18
    9/32"9/16"7/16"500000000000000
    5/16"-18
    5/16"1/2"17/32"1000000000000000
    5/16"-24
    9/32"9/16"7/16"500000000000000
    5/16"-24
    5/16"1/2"17/32"1000000000000000
    3/8"-16
    5/16"5/8"1/2"500000000000000
    3/8"-16
    3/8"9/16"5/8"500000000000000
    3/8"-24
    5/16"5/8"1/2"500000000000000
    3/8"-24
    3/8"9/16"5/8"500000000000000
    7/16"-14
    3/8"3/4"9/16"10000000000000
    7/16"-14
    7/16"5/8"11/16"10000000000000
    7/16"-20
    3/8"3/4"9/16"10000000000000
    7/16"-20
    7/16"5/8"11/16"10000000000000
    1/2"-13
    3/8"3/4"9/16"10000000000000
    1/2"-13
    1/2"3/4"13/16"10000000000000
    1/2"-20
    3/8"3/4"9/16"10000000000000
    1/2"-20
    1/2"3/4"13/16"10000000000000
    9/16"-12
    9/16"7/8"15/16"100000000000000
    9/16"-18
    9/16"7/8"15/16"100000000000000
    5/8"-11
    7/16"15/16"3/4"100000000000000
    5/8"-11
    5/8"15/16"1"100000000000000
    5/8"-18
    5/8"15/16"1"100000000000000
    3/4"-10
    1/2"1 1/16"7/8"100000000000000
    3/4"-10
    3/4"1 1/16"1 5/32"100000000000000
    3/4"-16
    3/4"1 1/16"1 5/32"100000000000000
    7/8"-9
    7/8"1 1/4"1 23/64"100000000000000
    7/8"-14
    7/8"1 1/4"1 23/64"100000000000000
    1"-8
    1"1 7/16"1 35/64"100000000000000
    1"-14
    1"1 7/16"1 33/64"100000000000000
    1 1/4"-7
    1 1/4"1 13/16"1 61/64"100000000000000
    M3 × 0.5 mm3.8 mm5.5 mm6 mmDIN 1587100000000000000
    M4 × 0.7 mm5.7 mm7 mm8 mmDIN 1587250000000000000
    M5 × 0.8 mm4.5 mm8 mm10 mmDIN 1587250000000000000
    M6 × 1 mm7.7 mm10 mm12 mmDIN 1587200000000000000
    M8 × 1.25 mm10.7 mm13 mm15 mmDIN 1587100000000000000
    M10 × 1.5 mm12.7 mm17 mm18 mmDIN 158750000000000000
    M12 × 1.75 mm15.7 mm19 mm22 mmDIN 158750000000000000
    M14 × 2 mm17.7 mm22 mm25 mmDIN 158710000000000000
    M16 × 2 mm20.6 mm24 mm28 mmDIN 158710000000000000
    M18 × 2.5 mm24.6 mm27 mm32 mmDIN 158710000000000000
    M20 × 2.5 mm25.6 mm30 mm34 mmDIN 158710000000000000
    M22 × 2.5 mm28.6 mm34 mm39 mmDIN 158710000000000000
    M24 × 3 mm30.5 mm36 mm42 mmDIN 158710000000000000
     
    Black-Oxide 18-8 Stainless Steel
    6-32
    5/32"5/16"11/32"1000000000000000
    8-32
    5/32"5/16"11/32"1000000000000000
    10-24
    3/16"3/8"13/32"1000000000000000
    10-32
    3/16"3/8"13/32"1000000000000000
    1/4"-20
    1/4"7/16"15/32"1000000000000000
    5/16"-18
    5/16"1/2"17/32"500000000000000
    3/8"-16
    3/8"9/16"5/8"10000000000000
    1/2"-13
    1/2"3/4"13/16"10000000000000
     
    Super-Corrosion-Resistant 316 Stainless Steel
    2-56
    5/64"3/16"3/16"100000000000000
    4-40
    5/32"1/4"1/4"500000000000000
    5-40
    1/8"5/16"11/32"10000000000000
    6-32
    5/32"5/16"11/32"500000000000000
    8-32
    5/32"5/16"11/32"500000000000000
    10-24
    3/16"3/8"13/32"500000000000000
    10-32
    3/16"3/8"13/32"500000000000000
    12-24
    7/32"3/8"13/32"10000000000000
    1/4"-20
    1/4"7/16"15/32"10000000000000
    1/4"-28
    1/4"7/16"15/32"10000000000000
    5/16"-18
    5/16"1/2"17/32"10000000000000
    5/16"-24
    5/16"1/2"17/32"10000000000000
    3/8"-16
    3/8"9/16"5/8"10000000000000
    3/8"-24
    3/8"9/16"5/8"10000000000000
    7/16"-14
    7/16"5/8"11/16"10000000000000
    7/16"-20
    7/16"5/8"11/16"10000000000000
    1/2"-13
    1/2"3/4"13/16"10000000000000
    1/2"-20
    1/2"3/4"13/16"10000000000000
    9/16"-12
    9/16"7/8"15/16"100000000000000
    9/16"-18
    9/16"7/8"15/16"100000000000000
    5/8"-11
    5/8"15/16"1"100000000000000
    5/8"-18
    5/8"15/16"1"100000000000000
    3/4"-10
    3/4"1 1/16"1 5/32"100000000000000
    3/4"-16
    3/4"1 1/16"1 5/32"100000000000000
    7/8"-9
    7/8"1 1/4"1 23/64"100000000000000
    7/8"-14
    7/8"1 1/4"1 23/64"100000000000000
    1"-8
    1"1 7/16"1 35/64"100000000000000
    1"-12
    1"1 7/16"1 35/64"100000000000000
    1"-14
    1"1 7/16"1 35/64"100000000000000
    1 1/4"-7
    1 1/4"1 13/16"1 61/64"100000000000000
    1 1/4"-12
    1 1/4"1 13/16"1 61/64"100000000000000
    M3 × 0.5 mm3.8 mm5.5 mm6 mmDIN 1587250000000000000
    M4 × 0.7 mm5.5 mm7 mm8 mmDIN 1587250000000000000
    M5 × 0.8 mm4.5 mm8 mm10 mmDIN 1587250000000000000
    M6 × 1 mm8 mm10 mm12 mmDIN 15872500000000000000
    M8 × 1.25 mm11 mm13 mm15 mmDIN 1587100000000000000
    M10 × 1.5 mm13 mm17 mm18 mmDIN 15871000000000000000
    M12 × 1.75 mm16 mm19 mm22 mmDIN 1587500000000000000
    M14 × 2 mm18 mm22 mm25 mmDIN 158710000000000000
    M16 × 2 mm21 mm24 mm28 mmDIN 158710000000000000
    M20 × 2.5 mm26 mm30 mm34 mmDIN 1587100000000000000
    M22 × 2.5 mm29 mm34 mm39 mmDIN 1587100000000000000
    M24 × 3 mm31 mm36 mm42 mmDIN 1587100000000000000
     

    Cap Nut Assortments

    Image of Product. Front orientation. Cap Nuts. Cap Nut Assortments.
    Image of Product. Front orientation. ZoomedIn view. Cap Nuts. Cap Nut Assortments.
    With a range of sizes on hand, you can use these assortments to conceal and protect protruding screw threads while fastening a variety of parts. Also known as acorn nuts, they have a smooth, rounded head that creates a finished look.
    18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.
    Thread Size
    No. of
    Pieces
    Container
    Type
    Each
    18-8 Stainless Steel
    6-32, 8-32, 10-32, 1/4"-20, 5/16"-18, 3/8"-16200Plastic Box0000000000000000
     

    Threadlocker Cap Nuts

    These nuts not only conceal and protect protruding screw threads, they also resist loosening from mild vibration. They have a nylon patch bonded to their threads that grips screws for a tighter hold than standard cap nuts. They’re reusable a handful of times, but the patch’s holding power decreases with each use. Also known as acorn nuts, they have a smooth, rounded head that creates a finished look.
    Stainless Steel
    Image of Product. Front orientation. Contains Annotated, Border. Cap Nuts. Threadlocker Cap Nuts.
    18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.
    Black-Oxide 18-8 Stainless Steel—Typically chosen for their appearance, these nuts have a dark, matte coating. They resist rust in wet and outdoor environments but won't hold up to the harsh chemicals that 316 stainless steel can.
    Super-Corrosion-Resistant 316 Stainless Steel—Our most corrosion-resistant cap nuts, these hold up in just about any environment. They won't degrade from exposure to weather, salt water, and most chemicals.
    Thread Size
    Thread
    Dp.
    Wd.
    Ht.
    Specs.
    Met
    Pkg.
    Qty.
    Pkg.
    18-8 Stainless Steel
    10-24
    3/16"3/8"13/32"5000000000000000
    10-32
    3/16"3/8"13/32"500000000000000
    12-24
    7/32"3/8"13/32"500000000000000
    1/4"-20
    1/4"7/16"15/32"500000000000000
    1/4"-28
    1/4"7/16"15/32"500000000000000
    5/16"-18
    19/64"1/2"17/32"500000000000000
    3/8"-16
    3/8"9/16"5/8"500000000000000
    3/8"-24
    3/8"9/16"5/8"500000000000000
    7/16"-14
    7/16"5/8"45/64"10000000000000
    1/2"-13
    1/2"3/4"13/16"10000000000000
    5/8"-11
    5/8"15/16"1"100000000000000
    3/4"-10
    3/4"1 1/16"1 5/32"100000000000000
    M5 × 0.8 mm5.6 mm8 mm10 mmDIN 1587500000000000000
    M6 × 1 mm5.7 mm10 mm12 mmDIN 1587500000000000000
    M8 × 1.25 mm8.2 mm13 mm15 mmDIN 1587500000000000000
    M10 × 1.5 mm9.7 mm17 mm18 mmDIN 1587100000000000000
    M12 × 1.75 mm12.2 mm19 mm22 mmDIN 1587100000000000000
     
    Black-Oxide 18-8 Stainless Steel
    10-32
    3/16"3/8"13/32"500000000000000
    1/4"-20
    1/4"7/16"15/32"500000000000000
     
    Super-Corrosion-Resistant 316 Stainless Steel
    10-24
    3/16"3/8"13/32"500000000000000
    10-32
    3/16"3/8"13/32"500000000000000
    1/4"-20
    1/4"7/16"15/32"500000000000000
    5/16"-18
    5/16"1/2"17/32"10000000000000
    3/8"-16
    3/8"9/16"5/8"10000000000000
    1/2"-13
    1/2"3/4"13/16"100000000000000
    5/8"-11
    5/8"15/16"1"100000000000000
     

    Distorted-Thread Cap Nuts

    For a stronger hold than nylon-insert cap nuts, these have irregularly shaped threads that grip the screw to resist loosening. The threads prevent the nut from backing out in high-vibration applications, but they also increase the effort to install and remove. To get these nuts off, you may need special tools, such as an impact wrench or propane torch. They have a smooth, rounded head that conceals and protects protruding screw threads while creating a finished look. Nuts are not reusable.
    Stainless Steel
    Image of Product. Bottom orientation. Cap Nuts. Distorted-Thread Cap Nuts.
    18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.
    Super-Corrosion-Resistant 316 Stainless Steel—Our most corrosion-resistant cap nuts, these hold up in just about any environment. They won't degrade from exposure to weather, salt water, and most chemicals.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Pkg.
    Qty.
    Pkg.
    18-8 Stainless Steel
    4-40
    5/32"1/4"1/4"10000000000000000
    6-32
    5/32"5/16"11/32"1000000000000000
    8-32
    5/32"5/16"11/32"1000000000000000
    10-24
    3/16"3/8"13/32"1000000000000000
    10-32
    3/16"3/8"13/32"1000000000000000
    1/4"-20
    1/4"7/16"15/32"1000000000000000
    1/4"-28
    1/4"7/16"15/32"1000000000000000
    5/16"-18
    5/16"1/2"17/32"500000000000000
    5/16"-24
    5/16"1/2"17/32"500000000000000
    3/8"-16
    3/8"9/16"5/8"500000000000000
    3/8"-24
    3/8"9/16"5/8"500000000000000
    7/16"-14
    7/16"5/8"11/16"10000000000000
    7/16"-20
    7/16"5/8"11/16"10000000000000
    1/2"-13
    1/2"3/4"13/16"100000000000000
    1/2"-20
    1/2"3/4"13/16"100000000000000
    5/8"-11
    19/32"1"63/64"10000000000000
    3/4"-10
    11/16"1 1/16"1 3/16"10000000000000
     
    Super-Corrosion-Resistant 316 Stainless Steel
    8-32
    5/32"5/16"11/32"10000000000000
    10-24
    3/16"3/8"13/32"10000000000000
    10-32
    3/16"3/8"13/32"10000000000000
    1/4"-20
    1/4"7/16"15/32"10000000000000
    5/16"-18
    5/16"1/2"17/32"10000000000000
    3/8"-16
    3/8"9/16"5/8"10000000000000
    1/2"-13
    1/2"3/4"13/16"100000000000000
     

    Sealing Cap Nuts

    Keep liquid, gas, debris, and other contaminants from seeping into or out of machinery, with no need for a separate O-ring. These nuts are often used outdoors to protect enclosures and other equipment from harsh weather. They also withstand high pressure, so they are useful for sealing pneumatic pumps and pressure valves. Also known as acorn nuts, they conceal protruding screw threads while fastening parts together and have a smooth, rounded head for a finished look.
    Stainless Steel
    Image of Product. Bottom orientation. Cap Nuts. Sealing Cap Nuts.
    18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Seal Material
    Seal Temp.
    Range, ° F
    Max. Pressure,
    psi
    Each
    18-8 Stainless Steel
    8-32
    5/32"5/16"5/16"Silicone Rubber-80 to 4001,20000000000000000
    10-32
    3/16"3/8"25/64"Silicone Rubber-80 to 4001,2000000000000000
    1/4"-20
    1/4"7/16"15/32"Silicone Rubber-80 to 4001,2000000000000000
    3/8"-16
    3/8"5/8"5/8"Silicone Rubber-80 to 4001,2000000000000000
    1/2"-13
    1/2"3/4"13/16"Silicone Rubber-80 to 4001,2000000000000000
     

    High-Profile Cap Nuts

    Three times the thread depth of standard cap nuts, these cover and protect extra-long, protruding screws, so you don't have to cut them when fastening parts together. They help prevent damage to surrounding materials and reduce injuries. Also known as acorn nuts, they have a smooth, rounded head that creates a finished look.
    Stainless Steel
    Image of Product. Front orientation. Cap Nuts. High-Profile Cap Nuts.
    18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Pkg.
    Qty.
    Pkg.
    18-8 Stainless Steel
    3/8"-16
    3/4"9/16"1 1/16"1000000000000000
    3/8"-16
    1"9/16"1 5/16"100000000000000
    3/8"-16
    1 1/4"9/16"1 9/16"100000000000000
    1/2"-13
    1"3/4"1 7/16"100000000000000
    1/2"-13
    1 1/4"3/4"1 3/4"100000000000000
    1/2"-13
    1 1/2"3/4"2"100000000000000
     

    High-Heavy-Profile Cap Nuts

    20% wider and taller than standard cap nuts, these have high, flat sides so your wrench won't slip off as you tighten. They cover screws to protect the threads and to prevent damage to surrounding materials. Also known as acorn nuts, they have a smooth, rounded head to create a finished look.
    Stainless Steel
    Image of Product. Bottom orientation. Cap Nuts. High-Heavy-Profile Cap Nuts.
    18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Each
    18-8 Stainless Steel
    1/4"-20
    3/8"5/8"5/8"00000000000000
    5/16"-18
    3/8"5/8"5/8"0000000000000
    3/8"-16
    15/32"3/4"3/4"0000000000000
    1/2"-13
    19/32"7/8"15/16"00000000000000
    5/8"-11
    25/32"1 1/16"1 3/16"00000000000000
    3/4"-10
    29/32"1 1/4"1 3/8"00000000000000
    7/8"-9
    1 1/16"1 3/8"1 5/8"00000000000000
     

    Sanitary Cap Nuts

    With extremely smooth sides and rounded edges, these nuts are free of crevices where bacteria can grow. Use them to cover and protect exposed threads while fastening parts together. Nuts are certified by EHEDG to meet sanitary design standards. They have a silicone seal on the base that keeps liquid, debris, and other contaminants off the threads. The seal is made with metal and chemical additives, so you can find it with a metal detector or X-ray machine if it falls into your line. Also known as acorn nuts, these have a domed head to create a finished look.
    Stainless Steel
    Image of Product. Front orientation. Cap Nuts. Sanitary Cap Nuts.
    Super-Corrosion-Resistant 316 Stainless Steel—Won't corrode from frequent washdowns and can stand up to the harshest cleaners and detergents.
    Thread Size
    Thread
    Dp.
    Wd.
    Ht.
    Seal Material
    Certification
    Food Industry Std.
    Each
    Super-Corrosion-Resistant 316 Stainless Steel
    1/4"-20
    1/4"7/16"21/64"Silicone RubberEHEDG Certified
    FDA Compliant 21 CFR 177.2600
    00000000000000
    5/16"-18
    9/32"1/2"25/64"Silicone RubberEHEDG Certified
    FDA Compliant 21 CFR 177.2600
    0000000000000
    3/8"-16
    5/16"9/16"15/32"Silicone RubberEHEDG Certified
    FDA Compliant 21 CFR 177.2600
    00000000000000
    7/16"-14
    21/64"11/16"33/64"Silicone RubberEHEDG Certified
    FDA Compliant 21 CFR 177.2600
    00000000000000
    1/2"-13
    11/32"3/4"35/64"Silicone RubberEHEDG Certified
    FDA Compliant 21 CFR 177.2600
    00000000000000
    5/8"-11
    7/16"15/16"43/64"Silicone RubberEHEDG Certified
    FDA Compliant 21 CFR 177.2600
    00000000000000
    M6 × 1 mm5.5 mm10 mm8 mmSilicone RubberEHEDG Certified
    FDA Compliant 21 CFR 177.2600
    00000000000000
    M8 × 1.25 mm6.5 mm13 mm10 mmSilicone RubberEHEDG Certified
    FDA Compliant 21 CFR 177.2600
    00000000000000
    M10 × 1.5 mm8 mm16 mm12 mmSilicone RubberEHEDG Certified
    FDA Compliant 21 CFR 177.2600
    00000000000000
    M12 × 1.75 mm9 mm18 mm14 mmSilicone RubberEHEDG Certified
    FDA Compliant 21 CFR 177.2600
    00000000000000
    M16 × 2 mm10.5 mm24 mm17 mmSilicone RubberEHEDG Certified
    FDA Compliant 21 CFR 177.2600
    00000000000000
     

    High-Profile Sanitary Cap Nuts

    Cover and protect 4" of exposed threads in food plants and other sanitary environments with these extra-long cap nuts. They are free of crevices where bacteria can grow and have a silicone seal on the base to keep liquid, debris, and other contaminants off the threads. The seal is made with metal and chemical additives, so you can find it with a metal detector or X-ray machine if it falls into your line. Nuts have a smooth, rounded head to create a finished look.
    Stainless Steel
    Image of Product. Bottom orientation. Cap Nuts. High-Profile Sanitary Cap Nuts.
    304 Stainless Steel—Won't corrode from frequent washdowns and can stand up to most cleaners and detergents.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Seal Material
    Food Industry Std.
    Each
    304 Stainless Steel
    5/8"-11
    29/32"7/8"4 5/32"Silicone RubberFDA Compliant 21 CFR 177.2600
    000000000000000
    3/4"-10
    29/32"1"4 5/32"Silicone RubberFDA Compliant 21 CFR 177.2600
    00000000000000
     

    Open-End Cap Nuts

    The open top allows threads to stick out slightly, so you don't have to worry about picking the wrong thread depth. These nuts also engage more threads than standard nuts for a tighter hold. The smooth, curved head creates a finished look, while still partially concealing and protecting the sides of the screw from damage.
    Stainless Steel
    Image of Product. Front orientation. Cap Nuts. Open-End Cap Nuts.
    18-8 Stainless Steel—The choice for wet and outdoor environments, these nuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.
    Thread
    Size
    Thread
    Dp.
    Wd.
    Ht.
    Each
    18-8 Stainless Steel
    4-40
    1/4"5/16"1/4"00000000000000
    6-32
    1/4"5/16"1/4"0000000000000
    8-32
    1/4"3/8"1/4"0000000000000
    10-24
    5/16"7/16"5/16"0000000000000
    10-32
    5/16"7/16"5/16"0000000000000
    1/4"-20
    5/16"1/2"5/16"0000000000000
    5/16"-18
    5/16"9/16"5/16"0000000000000
    3/8"-16
    3/8"11/16"3/8"0000000000000
    1/2"-13
    1/2"3/4"1/2"0000000000000
     
    back to top