Aluminum Oxide Flap Wheels: 1/4inch – 20 Shank Aluminum Oxide Flap Wheels: 1/4″ – 20 Shank UPC# Size Spec Carton Quantity 30,000 R.P.M. 39964 1 X 1 X 1/4 – 20 40 10 39965 1 X 1 X 1/4 – 20 60 10