Fits our range of modular Rifle, SMG and Pistol HPA Adapters Not compatible with our AK, Saiga, or MK23 HPA Adapters M4 Base - *INJECTION MOULDED* Made from ultra-durable polycarbonate. Impervious to BB hits Jet black finish that better matches your mags and receiver Excellent fitment with an optional shim system for rarer M4 mags Angled M4 Base - *INJECTION MOULDED* 'Speedsoft' Compatible Angle Made from ultra-durable polycarbonate. Impervious to BB hits Jet black finish that better matches your mags and receiver Excellent fitment with an optional shim system for rarer M4 mags MP5 Base Compatible with all CYMA MP5 Mid Cap magazines. Drum Allows your HPA adapter to be used with a Tokyo Marui MP5 or VZ61 drum (or a Well/Jing Gong one if you can find them). The drum itself can be purchased separately here Shotgun Shell Base (SMG) Allows your HPA adapter to be used with CYMA Shotgun Shells - Styled like an SMG / Extended GLK magazine Shotgun Shell Base (M4) Allows your HPA adapter to be used with CYMA Shotgun Shells - Styled like a modern AR magazine NONE - BASE UNIT ONLY We use this only to track stock. You will not receive anything if you add the 'NONE' option to your cart. Please stop doing this DO NOT EXCEED 150PSI WITH ANY AIRSOFT HPA ADAPTER. ALWAYS USE AIR REGULATED BY A SECONDARY REGULATOR (EG AT200, WOLVERINE STORM, POLARSTAR MRS). CHECK YOUR PSI BEFORE CONNECTING AIR TO A HPA ADAPTER. NEVER CONNECT OUR EQUIPMENT TO PAINTBALL AIR TANKS OR CO2 TANKS.NEVER CONNECT OUR EQUIPMENT TO A TIPPMAN STYLE HPA LINE