Surface Quality:S/D (Scratch/Dig)

Abstract: The scratch-and-dig designation for a component or assembly is specified by two numbers. The first defines allowable maximum scratch visibility, and the second refers to allowable maximum dig diameter, separated by a hyphen.

80/50 represents a commonly acceptable cosmetic standard
60/40 represents an acceptable standard for most scientific research applications.
10/5 represents a precise standard for very demanding laser applications