Q.R.S. is best upgrade stock for AR style Rifle, Fit with any mil-spec buffer tubes Q.R.S. is the first collapsible stock has multiple battery space, Not only supporting multi type batteries, like Bar-shapes. Twin-types..., but also storing tools. IR sticks. marker pens for mission executing. VFC QRS Stock (Black) Optional Q.D. Sling Mount Design M1913 Under Rail for additional equipments Made by nylon Fiber with extra heavy duty sling slot Instinctive latch design, keep your muzzle direction in adjusting Advanced Industrial design with user module construction Ready for futute QRS system expansions