any former Airborne / Paratroopers? is this device used for hooking up before a jump?

Paratroopers use mouth guard to stress-test helmet protection

Airborne patched Garrison Caps : r/army

DISPATCH: 82nd Airborne Paratroopers Doing What They Do Best

Airborne School: What It's Really Like Learning to Jump > U.S.

Paratroopers carry reserve chutesand sometimes flotation

Stand up, hook up, shuffle to the door, jump right out and count

Us army airborne paratroopers jump hi-res stock photography and

Paratroopers 82nd airborne divisions 1st hi-res stock photography

An Unforgettable Day – Pieces of History