✅ Heat treated tool steel 6150 - Rockwell hardness 50-52 ✅ Aerospace grade #2024 Aluminum piston ✅ Compatible With Hitachi NT65M2 Finish Nailer ✅ NT65M2SM 2 1/2 Inch 16 Ga Finish Nailer With Blow Nozzle ✅ NT65M2S Nailer