Granite Surface Plate Pink 2-Ledge Grade A Inspection Surface Size (In.) 12 x 18 Surface Size (mm) 300 x 450 Thickness (In.) 4 Thickness (mm) 100 Flatness Unilateral Tolerance (In.) 0.000100 Flatness Unilateral Tolerance (mm) 0.0025 Weight (Lbs.) 85 Weight (Kilograms.) 39