Package includes: 1 x CN70 Piston Driver, 1 x CN37526 Head Valve Piston, 1 x CN37547 Head Valve Washer, 1 x KK23195 Compression Spring, 1 x CN37525 Piston Stop, 2 x HH19195 O-Ring (Outside), 1 x HH19142 O-Ring (Inside) For Max CN70 Coil Nailer CN70 Parts, replace SP CN81204 piston driver Mechanically locked piston driver interface. This professional piston drive is for MAX CN70 coil nailer. Heat treated S7 steel at the tip of the piston to Rockwell hardness of 55~56. The cap end is at about 52. The piston driver cap is made of Aerospace Aluminum grade 7075.