Every pilot should have one hook knife on each harness they fly with.

Hook knives are used for the following reasons:

if you are unable to release your tow bridle
if you are getting dragged across the ground by a deployed reserve but can't disable it
if you land in the water and can't get out of your harness/lines etc.
if you are in a tree and need to cut yourself or your glider free
if someone is hurt and needs to be cut out of their harness etc.

There are replaceable blades stored in the handle.

These knives are the industry standard and are 8 inches long.

Comes in colors shown (red pouch, black knife)

Hook Knife - Jack The Ripper