FREE SHIPPING 315MM (12.402") DIAMETER 2.5MM (0.098") THICKNESS 40MM (1.575") ARBOR HOLE BOLT HOLES: 4/12/64 + 2/9/55 (4/12/64 = 4 bolt holes which are 12mm in diameter on a 64mm bolt circle) The bolt circle is the distance from the center of one pinhole to the center of the other pinhole directly across the arbor hole.Please verify you order the correct arbor size. HSS M2 DMo5 VAPOR STEAM TREATED BLACK OXIDE All cold saw blades used to cut steel products should have a coating. The most common coating is black oxide, sometimes referred to as vapor steam coated. The coating is most important to help prevent galling. Galling is caused by friction between sliding surfaces, most commonly found in metal on metal applications when there is inadequate lubrication between the surfaces. The combination of the coated blade and your flood coolant will prevent this issue. All blades are ground in the US on advanced computer numerically controlled (CNC) grinding equipment by industry experts with over 40 years of industry experience.