Increase the capabilities of your TM M4A1/SR16/M733 replicas with this Bore up kit. It includes a reinforced cylinder, cylinder's head, and piston's head designed specifically for these replicas. By increasing the diameter of the main air system, the kit allows for a greater muzzle velocity without the need for a stronger main spring. This also contributes to the longevity of the replicas. Each component in the kit has been reinforced for maximum performance, making it ideal for use with stronger springs. The double sealing of the cylinder's head and reinforced sealed nozzle ensure superior sealing compared to standard parts. The directional piston's head is also specially designed for quiet operation. Please note that a main spring of M120 or stronger is needed for proper operation. The kit includes a cylinder, cylinder's head, piston's head, and sealed nozzle, all made of durable polycarbonate and metal materials. Perfectly crafted for TM M4A1/SR16/M733 replicas, this Bore up