Package Includes: 888-588 Aftermarket Piston Driver Assembly 1 pcs. Compatible With: Hitachi NR38AK, PneuTools MC150, Senco JoistPro 150XP. Heat treated tool steel 6150 - Rockwell hardness 50-52, Aerospace grade #2024 Aluminum piston. These parts install quickly to make your nailer work like new again. A brand-new, unused, unopened, undamaged item in its original packaging. Return refund: If you have any questions, you can refund in full without any problems.