FlexLoc® (generically called flex lock nuts or flexlock nuts) self-locking nuts are one piece, all-metal, prevailing torque lock nuts. They work well in spite of impact, shock, and/or vibration. They lock without seating, and stay in place once the locking threads are fully engaged- so they can also be used as stopping nuts. These are available commonly in steel, though a few smaller sizes are also available in stainless steel.