Cheek Pad, Cheek Riser, Comb raiser, what ever you call it , this rugged injected molded ABS plasic construction makes this Tactical Cheek Pad the most durable one made for the M-4 stock . Two piece base assembles around stock and is held together with top pad that slides onto rail, locking the two sides together. No tools necessary to mount or remove this cheek pad. A 1 1/4" pad is included  for most optic sights and mounting on the carry handle top m-15. The pad base is designed to fit original Colt style M-4 tactical stocks and may need to be altered to fit after market and some later manufacturers stocks with different outside dimentions and bottom lug. Easily done with a dremel tool with a grinding bit.