Aftermarket for Senco SN4 SN70 Bumper BB0018Bumper / Piston Stop p/n BB0018 For Senco SN4 SN70 SN3 AST4 Framing Nailers.Available Qty: 1 Post navigation Senco SN325 Framing Nailer Rebuild kits SN4 O-ring kit + LB3500 + bumper BB0018