Bell & Gossett brass impeller, 3-7/8" outside diameter, for B&G Series LD3 and 2-1/2 booster pumps. Impellers are installed on the end of the pump shaft, which spins the impeller in turn pumping water, or other liquid, throughout your system.REPLACES ARMSTRONG 816305-058Replaces P/N P-07900, PB-4-Z-1235Used On:102219 2-1/2 IN. BI Pump Bronze Impeller .25 HP Single Phase102220 2-1/2 IN. AB Pump All Bronze .25 HP Single Phase102223 LD3 BI Pump .25 HP Single Phase102224 LD3 AB Pump All Bronze .25 HP Single Phase