This is a Limbsaver Sling known as the SW Tactical Sling, model 12139.
Limbsaver's tactical sling is designed to increase the stability of your weapon and reduce shoulder fatigue while carrying your gun. Its lightweight contour design is made out of LimbSaver's proprietary material which helps to evenly distribute the weight of your firearm over a larger area" relieving your shoulder of pain and fatigue. The sling has two military-grade quick-connect clasps for single and dual point connection" as well as a quick release clip for ease of use. It also uses high-strength nylon webbing" is fully adjustable and is intended for either right or left-hand use.
Features:
Military grade quick connect clasps
Uses high strength nylon webbing
Fully adjustable
