ICS MA-54 Upper Gear-Box D

Ideal for all short and standard barrel M4 models. The special upper gear box package will increase the convenience of upgrading FPS in every game, improving power within 1 minute.
package contains:
1.MA-34 Upper gearbox
2.MC-39 M120 Spring
3.MA-46 Metal spring guide(II) with screw
4.MA-50 Tappet plate and with spring
5.MP-23 Bolt
6.MC-56 Oversize piston head
7.MC-05 Aluminum piston
8.MC-58 Large Cylinder (4 hole)