D.R. Locking Collar part# 242261 is used on the 16.50 Pro DR Rapid Feed Chipper to hold the tow wheels on the axle. This locking collar has an inside diameter of 3/4" and an outside diameter of 1-1/4". There are many more uses for this part than we could ever list here, basically anywhere that you need a mechanical stop on a 3/4" shaft.