Check the listing for details. Crye Precision - Extendable STKSS for CPC Vest - Black. Color: Black, Condition: New with tags. Listed at 64.95 USD. Crye Precision CPC Extendable STKSS Model: BLC-X28-00-000 Color: Black Authentic, Brand New & Factory Sealed Product Description: Our STRUCTURAL KINETIC SUPPORT SYSYTEM (StKSS)™ allows a wearer to selectively transfer some or all of the weight of their armor vest to their hips. CPC™ 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 CPC™, LOW PROFILE BLAST BELT™, and AVS™ LOW PROFILE BELT. (Use CHASSIS™ StKSS™ ADAPTER for compatibility with CAGE ARMOR CHASSIS™ and HIGH BACK BLAST BELT™.) Made in the US from US materials. Features Extremely simple and lightweight Reduces back fatigue Highly flexible and easy to use Very little impact on range of motion Doesn't limit the vest's emergency-release capability Adjusts on the fly for perfect fit Weight 0.13 lbs. per piece (0.26 lbs. per pair)