ZFE Brass Wire Cup Brush Fits Dremel Rotary Tool Accessory Finish Pack Of 18Pcs 18 Pcs Brass Wire Cup Brush Fits Dremel Rotary Tool Accessory Finish 18 pack 1/2-inch (15mm) diameter brushes total (18 pack Brass). 18 Pack Of Brass Wire Brush Cup Bit diameter inch: 1/2-inch (15mm) Shank Size 1/8-inch (3mm)