Massacre Mod Kit for Nerf Alpha Trooper This kit includes metal trigger catch, 2x double strength trigger catch springs, rear reinforcement plate, 5+ kg mainspring (2.5kg stock), polycarbonate bolt sled with pin, polycarbonate breech with o-ring, polycarbonate plunger, and silicone grease. When installed, the Alpha Trooper shoots 75-80 fps muzzle velocity with up to 65ft range (parallel to ground) and up to 80ft range (30 degrees angled to ground) with streamline darts. WARNING: Does NOT work for Elite Alpha Trooper. Mod at your own risk! Increasing the spring tension can break or damage stock internal components of your blaster. Blaster not included.