6-1/2" msnry abrsv blade. Masonry cutting, industrial quality blade. Ideal for cutting and chopping applications on all 7" and 8" circular saws. Metal arbor to prevent shearing. 5/8" round, diamond arbor. 6-1/2" diameter, maximum speed: 9400 RPM No. DW3521: 7" diameter, maximum speed: 8700 RPM No. DW3532: 8" diameter, maximum speed: 7600 RPM