This 36pcs polishing wheel set are made of high quality brass and steel material, durable and sturdy to use. They are mainly used to remove the rust of metal surface, suitable for working with electric rotary tools such as angle grinder, electric drill, etc. Made of high quality brass and steel material, sturdy and durable with long service life. Fine workmanship ensures their great polishing performance. 36pcs polishing wheels with different shape and size can meet your different requirements, economical and practical. Can work with various rotary tools such as angle grinder, electric drill, etc. Great tool for paint and rust removal, weld cleaning, rough surface treatment and more. Specification: Material: Steel, Brass Shape: Pen, Flat, Cup Shank Diameter: 3mm/0.12in Outer Diameter: 6mm/0.24in (Pen), 20mm/0.79in (Cup),25mm/0.98in (Flat) Weight: Approx. 183g/6.5oz Package List: 6 x Pen Shaped Steel Wire Brush 6 x Pen Shaped Brass Wire Brush 6 x Flat Shaped Steel Wire Brush 6 x Flat Shaped Brass Wire Brush 6 x Cup Shaped Steel Wire Brush 6 x Cup Shaped Brass Wire Brush Note: Please allow slight error due to manual measurement. Thanks for your understanding.