A-B11667335SM-AI COLLAR, SET, 1.251 XOne New Aftermarket Replacement Set Collar for Murray, Snapper, and Simplicity Snow Throwers and Snow Blowers This 1. 251 inch set collar is a shaft positioning and retention component used in the drivetrain and auger drive assemblies of two stage snow throwers and snow blowers made by Murray, Snapper, and Simplicity (all Fits Briggs & Fits Stratton family brands). It locks onto the shaft to secure rotating components and maintain proper spacing and