Probably the toughest brushes in the world and they need to be, bearing in mind the work they are called on to do. Used for heavy duty cleaning operations, de-rusting, cleaning welds, etc. Offered in two forms, either crimp wire or heavier duty twist knot. A word of caution - before ordering check your grinder's speed. The greater the brush diameter the lower the maximum permitted safe speed - given in brackets with the stock description.