This is a replacement part manufactured for use with snow throwers.This special worm gear drives the auger shaft and has a key slot in the arbor to fit onto the output shaft using a woodruff key.Part Number: 717-0528A, 717-0528, 917-0528A, 717-04449, 717-04861, 917-0528, 917-04861Fitment:Fits Various Bolens, Columbia, Craftsman, Gold Series, Huskee, MTD, MTD Gold, MTD Pro, Ranch King, , Troy-Bilt, Yard Machines and Yard-Man modelsFor MTD 917-04861 20T Worm Gear Fits Bolens Craftsman Troy-Bilt CadetColour:GoldMaterial:metalsize:OD:1 7/8 inchID:3/4 inchTeeth:5/8 inch W- 20Package Contents:1 x Worm GearOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.