GunsModify CNC RMR Zero Blow Back Housing for Marui G17 GBB
CNC Aluminium Construction
The new Zero housing design allows better durability and stability when used with Guns Modify Zero hammers with enhanced hammer springs.
Feather Weight Piston increase operating speed and improve efficiency of each shot
Come with Steel Hammer & Steel Sear
Suitable for Tokyo Marui G17 Series Airsoft Gas Blow Black GBB Pistol (with RMR Cut Slid)

As always, upgrading GBB require necessary skill & technique, consult expertise if needed