Blue Zirconia High Density Kassteel Jumbo Flap Discs. Type T27. Pack of 10. Best used for grinding and polishing of metals, blending of welds and metal finishing. Individual Zirconia sanding strips on a Y weight polyester cloth backing are bonded to a fiberglass backing plate in a circular pattern. Flaps are overlapped and a new layer of the sanding strip is exposed as each previous layer wears away, resulting in a consistent cut rate through the life of the flap disc. Due to the overlap of the abrasive strips this product provides a cooler and more efficient grinding process than conventional fiber discs. Use on a right angle grinder.