PFERD stringer bead knot power wheel brushes. Stringer bead knot wheel brushes are tightly twisted for low flex, high impact brushing action. Designed for root and hot pass weld cleaning in pipe joining applications. Also for general use where a narrow face, aggressive brush is desired for controlled, confined surface contact area. Root and hot pass weld cleaning, applications requiring most aggressive brushing action. Knot wheel brushes with threaded hubs for fast and easy tool changes. Superior rotational balance reduces operator fatigue and improves tool life. Recommendation for optimal performance, use on angle grinders. 56 Knots. 1-1/8-inches trim length. 3/16-inches face width. 5/8"-11 thread size. Uses in industries area: automotive, transportation, mining, electronics, aerospace, welding, nuclear, textiles, food services, construction, petrochemical, farming, medical, shipbuilding, fabricating, defense, foundries and plastics.