Super Light CNC 7075 Aluminum Housing for Marui / WE Hi-Capa 5.1 Airsoft GBB [For Airsoft Only] Super Light Weight Speed Piston Housing CNC aluminum construction Feather weight piston increase operating speed and improve efficiency of each shot Suitable for Tokyo Marui / WE Hi-Capa 5.1 series airsoft gas blow back GBB pistol As always, upgrading GBB require necessary skill & technique, consult expertise if needed