Hydraulic buffer kit smooths out the recoil impulse of a straight blowback PCC. The heavy damping profile is best for suppressed applications or unsuppressed barrels longer than 8a ^2. Specifications: Buffer weight: 6oz Heavy Damping Buffer length: 4.35a ^2, when compressed 3.90a ^2. (no need for a buffer spacer) Bumper color: Black Contents include: 6oz hydraulic 9mm buffer Carbine buffer spring