Arbor hole for easy mounting to grinder shaft.For minor finishing and blending applications.Less aggressive cutting than traditional surface conditioning discs.Great for final finishing prior to buffing with compounds.Use the slowest speed possible for optimum results., Medium (General Purpose): Use for light finishing after using surface conditioning discs; excellent for blending surface imperfections, coated abrasives.Very Fine: Excellent for blending surface imperfections, final finishing and preparation prior to coating. Use the Very Fine grade followed by the SAIT Buffing Discs and compounds for a near mirror finish.