Leapers, Inc. - UTG UTG PRO, Mil-spec Stock Kit, Black Finish, Fits AR-15, Compact Size, Includes Cheek Rest Plus Removable Extended Cheek Rest Insert, Rubberized Butt Pad, Mil-spec Extension Tube, Buffer, Buffer Spring, Receiver End Plate and Castle Nut, Flat Dark Earth RBUS4DM This is a UTG PRO AR-15 Ops Ready S4 Mil-spec Stock Kit molded from impact resistant high strength matte black polymer. It is complete with Mil-spec extension tube" buffer" buffer spring" receiver end plate" and castle nut. Its unique 4.28" length with 4 position adjustability provides comfortable length of pull and ease of shouldering firearm when wearing a load bearing vest or plate carrier system. It is built for heavy duty use with the tightest tolerance controls to provide the most secure fit and function. Flat dark earth finish.