When you really need a cutting tool, the simplest solution is often best.  The DIR knife is as simple as it gets, and won’t slow you down when you need it the most.

A simple short serrated stainless steel blade mounted to a sturdy plastic handle is securely held into the nylon sheath from pressure and friction alone.  This eliminates the need for straps or buckles to tangle up and slow you down when deploying the cutting tool.  The sheath can be mounted on any 2 inch webbing, most commonly on the diver’s left hip. 

Often the simplest solution is best.  And seriously, this is as simple as it gets.