Oregon 78-013 Flat Idler Pulley Lawn Mower Idlers Oregon 78-013 Replacement Flat Idler Pulley 4" Outer Diameter, 3-1/16" flat Outer Diameter 1" flat width, 3/8" bore, 1/8" offset Replaces AYP 177968, Poulan 532177968, 532193197, 193197