Circulating Pump Coupler, Compatible with Brand Armstrong, Bell and Gossett, Compatible with Grainger Part Number 52CE11, 52CE13, Compatible with Manufacturer Model Number 106284MF-132, 106284MF-133, 106285MF-132, 106285MF-133, 116439MF-132, 116440MF-133, 116443MF-136A, 116444MF-137A, 116452MF-133, 116455MF-136A, 116456MF-137A, Compatible with Series 1050-1.5, 1050-2, H-53, H-54, S-55, S-57, Compatible with Series Family 1050, S&H, Coupling Material EPDM, Number of Splines 18