3M™ B0083 Spindle, 1/4-20 Int, 1 Pkg Qty Well-built steel spindle that the backup pad screws into. Has a 1/4-20 Internal thread. Used on 3 in 3/32 in Orbit Random Orbital Sanders.
3M™ B0312 Spindle, 1 Pkg Qty Well-built steel spindle that the backup pad screws into. Has a 5/16-24 Internal thread. Used on 3 in Random Orbital Sanders with 3/16 in orbit.