Oscillating Belt/Spindle Sander Model 50-310 is a specialized sander for the fast and accurate sanding of curved board edges. The 4 x 24 belt and spindle sandling sleeves oscillate up-and-down 5/8, 58 time per minute while the spindle spins, providing more efficient abrasive cutting action. Includes 4-1/2 long 80 grit abrasives.