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:51 x 8mm / 2.01 x 0.31inch (L*D)Shank Size: 20 x 5.5mm / 0.79 x 0.22inch (L*D)Drilling Diameter: 8mm / 0.31inch