The SMD is an armored diamond which is usually used for carbide and steel applications in a 50/50 ratio. The 110 grit is on the course end of the spectrum for a super abrasive and should give a finish of around 32RA. This wheel has an R grade resin. This wheel was purchased with a machine and is still in it's original factory crate. SPECIFICATIONS: Shape............9A1 Outer Diameter............18" Width............10" Bore............8" Grit Layer Depth............1" Abrasive Type............SMD Grit Size............110C Bond Type............B Bond Number............XD3027 Grade/Exposure Code............R Concentration............110 Core Type Code............Bakelite Plants............4290 Drawing Number............MC300731 Dimension String............9A1A 18 X 10 X 8 Market Specification............PCD121-B-1 MOS RPM............2020 *Preliminary specifications, pending confirmation