Feature●904685 FN250B Fits for Piston Stop 16 Gauge Finish Nailer●Acts as cushion when the piston/driver retracts back into the cylinder after being fired.●Part number: 904685●Fits models: FN250B Type 1, FN251 Type 1●This component acts as a buffer when the piston/driver retracts back into the cylinder after ignition.Description