Military strap as worn by French Army combat swimmers*.
Handmade, in France by Arnaud le Cavorzin from vintage parachute rappelling webbing (army stock, new) and hardware also from parachute bags.
100% military origin including stitching thread! (Nato green polyamide nylon from Zwicky’s, used by the army).
*the story goes like this. It was in the 1970s. Equipped with absolutely flawless watches (whose names start with a T. and end with an r.) but equipped with leather straps, the combat swimmers of the French Navy developed this practical and clever object that allowed their waterproof watch to follow them in the water. True utilitarian and efficient design.
N.B. As you can see on the second picture, the strap is delivered in a military pouch which originally contained the soldier’s sewing kit.