Great for use with sanding papers to sand and finish the inside of rings Made of stainless steel and come with rubber bands to hold paper in place Includes 3 mandrels, 1/4 inch, 3/8 inch and 1/2 inch 3 millimeter shanks (1/4 and 3/8) and 4 millimeter shank (1/2) Shanks are 5/8 inch long; maximum 10,000 RPMs