compatible with the following machines: Compatible with NV45AA Heavy Duty Coil Nailer. Compatible with NV45AB 1-3/4" Heavy Duty, Roofing Coil Nailer. Compatible with NV45AB2 Side Load Coil Roofing Nailer. Compatible with NV45AB2(S) Bottom Load Coil Roofing Nailer. Compatible with NV45AB2M 1 3/4 Inch Roofing Coil Nailer Side Load Magazine Compatible with NV45AB3 Nailer Compatible with NV45AE 1-3/4" Side Load Coil Roofing Nailer Compatible with NV45AES Nailer Compatible with NV50A1 Light-Duty Coil Utility Nailer Compatible with NV50A1M 2 Inch Utility Coil Nailer (Wire Collation) Compatible with NV50AP2 Full Round Head, Coil, (Wire Collation) Installation Method： 1.remove the retaining ring from the feeder shaft. 2.Slide the feeder with feeder spring off of the shaft. 3.The old spring can now be removed and the new one set in place. 4.Slide the feeder with spring back onto the feeder shaft and secure with the retaining ring.