When hand pressure is released, these wrenches automatically pop out of lathe chucks to keep users and machines safe from harm. Use them to prevent accidents that can occur when someone forgets to remove their wrench before turning on a lathe. Also known as lathe chuck keys, the long T-handle on these wrenches gives you the leverage you need to open tight lathe chucks. For a secure grip, the handle on the square-drive wrenches has knurled ends, while the handle on the hex-drive wrenches is coated with PVC.