Adjustable pulley for evaporative cooler motor. Made of zinc. No. 6123: Size: 3-1/4" Dia x 1/2" OD Bore, Motor Size: 1/3 HP, Material: Zinc No. 6144: Size: 3-3-1/2" Dia x 1/2" OD Bore, Motor Size: 1/2 HP, Material: Zinc No. 6151: Size: 3-3/4" Dia x 1/2" OD Bore, Motor Size: 1/2 HP or 3/4 HP, Material: Zinc, Pkg Qty: 1, Package Type: Bag No. 6170: Size: 4" Dia x 1/2" OD Bore, Motor Size: 1 HP, Material: Zinc, Pkg Qty: 1, Package Type: Bag No. 6172: Size: 4" Dia x 5/8" OD Bore, Motor Size: 1 HP, Material: Zinc, Pkg Qty: 1, Package Type: Bag