Do you find your cylinder system riding up and banging into the back of your head? This can be annoying and possible dangerous. Yet, there is an easy fix for this problem. Adding a crotch strap to your back pack set up can not only eliminate the problem, but give you increased stability when diving. The Hollis Crotch strap and is easy to install on your back pack assembly. An Added Bonus the completely adjustable strap comes equipped with a Scooter Ring which allows you to have you're DVP (Diver Propulsion Vehicle) lanyard to your gear when you want to let it go with your hands.