Blue Round Coarse 90 Grit Disc for rapid removal with smooth, coarse finish on contoured or concave surfaces. Holey Galahad is engineered to open a window to your work no stopping to lift the grinder and check your progress. Discs can be used on both their face and edge surfaces. Made of durable Tungsten Carbide, no heat build up. Fits most 4-1/2 inch (115 mm) and European 125 mm angle grinders with recessed universal nut. Maximum 14,000 RPM. Discs are 4 inch (100 mm) in diameter and feature patented structured tungsten carbide teeth bonded to steel discs over the total cutting surface. Tungsten carbide needles are manufactured in a 5-stage patented process.