Bell & Gossett bronze impeller for B&G Series 80 pumps with 1-1/4" shafts, model 804TB size 2x2x9-1/2B and model 805TB size 2-1/2x2-1/2x9-1/2. Impeller diameter must be specified when ordered as this impeller is trimmable. Impeller diameter will be found on the pump's I.D. tag. Impellers are installed on the end of the pump shaft, which spins the impeller in turn pumping water, or other liquid, throughout your system.