NSN 8465-01-683-9139:

The STRUCTURAL KINETIC SUPPORT SYSTEM (StKSS)™ allows a wearer to selectively transfer some or all of the weight of their armor vest to their hips. EXTENDABLE StKSS™ allow the wearer’s shoulders and spinal column to be completely isolated from the weight being carried. Instead, the weight is transferred directly to the pelvis (hip bone) and legs. The effect is unmistakable, and the benefit is undeniable to those familiar with what wearing a >50 lbs. vest for months on end does to your lower back. Compatible with AVS™ HARNESS , AVS™ LOW PROFILE BELT , and LOW PROFILE BLAST BELT™ . Made in US from US materials.

Features:

1. Extremely simple and lightweight
2. Designed to reduce back fatigue
3. Highly flexible and easy to use
4. Very little impact on range of motion
5. Doesn't limit the vest's emergency-release capability
6. Adjusts on the fly for perfect fit

Weight: 0.17 lbs. per piece (0.34 lbs. per pair)