High performance in cutting glass, slate, tile, porcelain etc.Tiny diamond particles coated tip offers sharp cutting.To prolong its using life, please remember to keep it with coolant sometimes.Specification:Product Name: Glass Hole Saw.Total Size:55 x 20mm / 2.17 x 0.79inch (L*D)Shank Size: 24 x 7.8mm / 0.94 x 0.31inch (L*D)Drilling Diameter: 20mm / 0.79inch