GT Airsoft shows how to do a conversion of the SCAR-H Gas Blowback Rifle to a SCAR 20 SSR. The base gun is a WE Airsoft SCAR-H GBB Rifle and used a WE SCAR 20 SSR upper conversion kit from KYAirsoft, a replica MAGPUL PRS Precision, and the Angry Gun SCAR Gen II Stock Adaptor.