For A belts pulleys from 2 to 12 in. have keyways except 3 8 and 1 2 in. bores and 3 4 in. bores in pulleys less than 4 in. in diameter. All pulleys are with slotted headless set screws. For 4L or 1 2 x 11 32 in. belts. Features . A Section. Die Cast. Size - 1 2 x 5