I love these things.  When my kit is stationary at home, I usually just have this permanently on my hihat stand's adjustment stop thing (the piece on the pole that allows you to quickly adjust it back to whatever height you set the clamp to).  It doesn't rattle and doesn't get lost.  When I gig though, I have to remember to grab it otherwise I'll lose it in transit.  I have two for when I change heads too.  It's perfect for thumb tightening opposing lugs quickly to seat the head relatively even.  I highly recommend these things!  I still have the cheapos laying around in case of an emergency, but these are my go-to keys.