The ORIGINAL Weight Adjustable piston is back, with an improved design and material tweaks. The SRS W.A.S.P package features: 1 x SRS W.A.S.P Base Piston body 1 x Rear Sear 1 x Rear Guide Ring 1 x Front securing Ring 1 x Plastic Sleeve (Light) 1 x Steel Sleeve (Medium) 1 x Steel Sleeve (Heavy) 1 x Non-Airbrake Fitting 1 x Full Airbrake 1 x Mid Brake 1 x Injection Moulded Cup 1 x One Piece Stainless Steel Spring Guide Spring Guide Orings (to fit new/old generations of buttpad) Notes: – When using the airbrake, please bear in mind this is only effective up to a certain point in terms of power gains over the non-airbraked setup. This is due to how the air works inside the cylinder, at a certain point the sheer power of the spring and piston result overrides the airbrakes function and slow to air down to much causing a loss. This “break point” will depend entirely on your setup. That being said, due to the guide ring and cup design alone, even at 4.5J, weighted and unbraked the sound is still reasonable. - Piston works with most 13mm springs. However some of the lower power SBA springs aren't the same spec and may bind - Ensure the cup is correctly lubricated before use, silicon oil is best. - Due to the rear guide design of the SRS W.A.S.P, you may need to lower your sear height to allow the sear to slide over and release. If you find the piston does not release or sticks, lower the sear height.