For Mil Spec (COLT)tubes only. Introducing the new Telescoping AR15/M16 stock with battery storage tubes on the side. This five position telescoping stock has two storage compartments with O-ring sealed screw in caps. The storage compartments are water tight and will hold two AA or three 123 Lithium batteries in each side. The stock has a nonslip hard rubber butt plate and three places to attach a sling These stocks have our life time warranty and built tough enough so you never have to use it.