ZFE Accessory For Dremel Rotary Tool 1/2" Wire Cup Brush Polishing Buffing Pack Of 18Pcs 18Pcs Accessory for Dremel Rotary Tool 1/2" Wire Cup Brush Polishing Buffing 18pack 1/2-inch (15mm) diameter brushes total (9 pack Steel & 9 pack Brass). 9 Pack - Brass Wire Brush Cup Bit diameter inch: 1/2-inch (15mm) Shank Size 1/8-inch (3mm)