Above the one-hand-open hole sits a feature called a Cobra Hood.  It's a metal cap that guides the thumb over the hole for quick, by-feel opening then doubles as a textured leveraging platform for your thumb during cutting. 

A wavy pattern cut out of the top of the blade and again along the handle is for controlled rope cutting. 

By placing a rope in the groove (between the partially open blade and handle) you can squeeze the blade shut, slicing and trimming rope in a controlled movement without fully exposing the cutting edge. 

The handle is black lightweight fiberglass reinforced nylon (FRN) with a survival whistle built into the butt end, shrill and high-pitched enough to get you noticed. 

A reinforced wire pocket clip attaches through the handle on either side for left- or right-hand use.  A retractable and replaceable carbide-tip glass/ice breaker is housed inside the handle and is exposed when the closed blade is squeezed into the handle, retracting when pressure is released.