These spring load pull pins allow you to quickly retract and engage the plunger for locating, fastening and quick change operations. They consist of two parts which include a housing (barrel) and a plunger assembly. The plunger assembly screws into the housing. The housing is designed to be welded into place for strength. The 3/8-16 threaded end allows the user to add a custom handle or other method of actuation. Pulling up on the plunger assembly retracts the plunger into the housing. Releasing the plunger assembly allows the spring loaded plunger to extend. The zinc plated steel plunger assemblies are made from C1038 steel on all sizes except the 5/8 which is made from 12L15 steel. The aluminum housings are made from 6061-T6. Pull up force is approximately 5 lbs.