18-8 Stainless Steel—The choice for wet and outdoor environments, these washers 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 washers have a dark, matte coating to create a finished look. They resist rust in wet and outdoor environments, but won't hold up to harsh chemicals as well as 316 stainless steel.

Super-Corrosion-Resistant 316 Stainless Steel—Superior to 18-8 stainless steel, these washers won't degrade when exposed to harsh weather, salt water, and most chemicals.

One-third the weight of steel, these washers are commonly used in robotics, automation, and other applications that have weight limits. They're an alternative to stainless steel for rust resistance, but aren't as strong.

Softer than most metals, brass washers won't damage other fastening components.

Brass—With a warm, polished look, these washers are often chosen for their appearance. Similar to 18-8 stainless steel, brass is corrosion resistant enough to stand up to wet environments.