The third in the Tokyo Marui Gas Blowback M4 Series, the M4A1 Carbine gets reviewed by Mach Sakai. This uses the ZET System for improved durability. Mach Sakai tests this for operation and performance and uses the Tokyo Marui's Gun Power Gas which the company claimes to be eco-friendly and has a patent pending proprietary blend ration of HFO1234ze + LPG.