Nine Ball High Bullet Valve for Tokyo Marui MP7A1 GBB SMG
Extreme Output Power upgrade
Increase the shooting power of each shot
Withstand high pressure airsoft gas
The ball bearings included with the Nine Ball Hi-Flow Valve are to be placed inside the gas reservoir to promote more consistent high-power gas release.

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