The MadBull PWS Diablo RIS Unit for M4 is an amazingly realistic looking replica of the famous piston driven firing system from PWS. The free float rail system and extremely aggressive compensator give this unit unique form and plenty of function. This is designed for a CQB set up. Madbull is leading the airsoft industry in real gun licenses, this allows them to legally put real gun trademarks on their high quality products. This is yet another excellent quality airsoft replica piece from Madbull.