Walter 13-G 304 Knot Twisted Cup Brush 3" (Box of 10) Walter Surface Technologies Sale! from 28000 /per Qty. Add to Cart This item is currently on backorder but you can still purchase it now and we'll ship as soon as more become available. Cup Brush, Knot Twisted Wire, 3" Diameter, .020" Wire, 5/8-11" Threaded Arbor Hole SKU:WLT 13G304