CYMA Plastic Hop Up Chamber Set for CYMA CM041 MP5 Series AEG Gearbox Rifles AirsoftCYMA Plastic Hop Up Chamber Set for CYMA CM041 MP5 Series AEG Gearbox Rifles Made out of plastic. Improves Firmness of the chamber and stabilizes the muzzle velocity. Fits most metal bodies (except KWA metal body). Fit tightly to the barrel base to keep the chamber being centered. Suitable for CYMA CM041 MP5 Series AEG Gearbox Rifles. Color Black Weight 9g Original Packing.