These spring loaded hand retractable plungers have a wide range of applications to lock items in place. They are used to prevent any change in position due to lateral force. Pulling up on knob retracts the plunger pin completely into the body and unlocks the mechanism. The knob is made from black plastic. The body and plunger pin are made from AISI-4140 alloy steel with a zinc-plated natural finish. The spring is made from 17-7 stainless steel.