When hand pressure is released, these keys 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 key before turning on a lathe. Also known as lathe chuck wrenches, the long T-handle on these keys gives you the leverage you need to open tight lathe chucks. For a secure grip, the handle on the square-drive keys has knurled ends, while the handle on the hex-drive keys is coated with PVC.