There are several items that are essential when putting together a Save-A-Dive Kit, Cylinder Valve O-rings, Fin Straps, Buckles, etc. One of the most important items is the spare knife strap. Two (2) different knife straps are universal and will fit a large variety of Knife Sheaths out there, one comes with general release buckle strap (1/8" thick,) another with Quick Release Buckle Strap (1/8" thick.) Don't let a bad Knife Strap be the causes of you not carrying your diver's tool, always have a spare. Strap is made of depth compensating rubber, so your knife won't get lose when your exposure suit compresses upon descent. Strap buckles are non-corrosive impact resistant plastic for long life and durability.