Package include: 1 x 878-179 Piston Bumper, 1 x 877-993 Bumper Sheet 1 X 878-156 Aftermarket Piston Driver 1 x 883901 Feeder Replacement Part, 1 x 877-761 Feeder Spring, 1 x 877-825 Feeder Shaft, 1 x 877-826 Shaft Ring Heat treated tool steel 6150- Rockwell hardness 50-52 Aerospace grade number 2024 Aluminum Piston For Models NV45AB2, NH451, NV45AB2(S), NT50A, NV45AE, NV45AA, NV50A1, NV45AB, NV50AP, NV50AP2, VH501, N5008A, NV45AB2M