A.Y. McDonald 21050M2A Bronze Well Pump & Motor 25 GPM 0.5 HP 115V 2-Wire Single-PhaseA. Y. McDonald offers a full line of four inch submersibles ranging from 1 3 through 5 horsepower, with flow rates ranging from 5 to 25 gallons per minute (GPM). Our 21000 submersibles offer peak capacity performance in 5, 7, 10, 15, 20, and 25 gallons per minute (GPM) models. All M Series No Lead Pumps come with a 1 1 4" discharge and sizes range from 1 2 to 5 horsepower (HP). Two wire models up to 1 1 2 horsepower (HP) or three wire models up to 5