Crown 41299 Circulator Coupler 1/2" x 1/2" For Many Of The Most Popular Circulators (This model is made of Zinc) Replaces Bell & Gossett 118705, 189110, PZ-429 Armstrong 806026-001 Hydrovalve RM-876 Sid Harvey 156, 156B, 156C Strainer Screeen & Cylinder SSC-779, 118705 Westwood H24-10, PD-40 Dayton / Grainger 4RD81