Almost all Corrections Officers have carried these keys at some point in their career... They are useful in locking up most inmate in the system... especially the aggressive ones; just make sure you don't forget to turn the lock back closed or you may have to deal with him or her again with your back to them, and that is not a good thing. We must all learn to appreciate the lock and remember this tool that we use to lock most of societies problems away from the rest of the world.