NEW PISTON DRIVER FOR HITACHI NV83A,NV83A2, PART NO. HITACHI 878-428 Description Aftermarket Hitachi Framing Nailer Piston Driver. This is a generic replacement driver with o-ring for the Hitachi NR83A, NR83A2, NR83A2(S) framing guns. This comes with a patent pending locking mechanism which will not allow the driver to unscrew from the piston. Aluminum is crimped into the unilok grooves of the shaft to prevent unscrewing. Heat treated tool steel 6150 - Rockwell hardness 50-52 Aerospace grade #2024 Aluminum piston Mechanically locked piston driver interface Specification: Heat treated tool steel 6150 - Rockwell hardness 50-52 Part Number SP 878-428 885-915 Package includes: 1x Piston Driver