B01 Blowback Housing is precision CNC machined from aluminium 7075 for ultimate durability and quality. Weighing in at just 18 grams, this blowback housing will improve the cycling action as well as gas transmission. Also, the special design on the piston head can let the O-ring always in perfect condition. It minimises the air leakage during the blowback action and the different sizes of anti-oil O-Ring provided can fit commonly used nozzles in the market. It can effectively cease that slight wobbling during the nozzle movement. The B01 Blowback Housing is compatible with Tokyo Marui Hi-CAPA / 1911 Series Airsoft GBB Pistols. Highlighted features Aluminium material with CNC machined Ultra lightweight design Durable construction prevents flexing and warping under hard use Provide stable and smooth blowback cycling Available in Black and Silver The screw for the piston is default loosen when packaging. User needs to tighten up for installation. Strong Screw glue is needed for installation. Use a drop of screw glue when installing the screw and wait for it to dry out overnight. Damage could be caused to the screw thread if screw glue was not used. *PS: Please note: installing parts / assemble /fitting airsoft gun will need intermediate knowledge; for expert or airsoft gunsmith. Please refer to your airsoft gunsmith for proper installation/fitting. Fitting may be needed as the condition of each airsoft gun might be different. Regular maintenance is needed for all airsoft guns in order to keep it in good working condition and reduce wear out issue on parts.