The popular B&T MP9, GBB sub-machine gun is a powerful CQB airsoft gun, and in some CQB ranges, it might be to powerful, this drop-in replacement part will reduce velocity with 15-22 m/s (50-70fps) putting the MP9 well below the maximum limits on airsoft ranges everywhere.The Low-power bolt assembly contains valve, piston and cylinder.

Installing this Downgrade bolt makes the Mp9 suitable for the UK in all temperatures