1. Zirconia flap disc,with fiberglass backing pad Size Arbor Grit Maxrpm Type 4? 5/8? 36# 40# 60# 80# 120# 15300 T27 T29 4-1/2? 7/8? 36# 40# 60# 80# 120# 13300 T27 T29 5? 7/8? 36# 40# 60# 80# 120# 12000 T27 T29 7? 7/8? 36# 40# 60# 80# 120# 8600 T27 T29 2. Aluminum Oxide flap disc,with fiberglass backing pad Size Arbor Grit Maxrpm Type 4? 5/8? 36# 40# 60# 80# 100# 120# 15300 T27 T29 4-1/2? 7/8? 36# 40# 60# 80# 100# 120# 13300 T27 T29 5? 7/8? 36# 40# 60# 80# 100# 120# 12000 T27 T29 7? 7/8? 36# 40# 60# 80# 100# 120# 8600 T27 T29 T-27/Flat ?Used when grinding on flat surface,correct angle recommended between 0-15 degrees,best choice for smooth finishing. T-29/Conical ?Built in angle for grinding,this design is excellent for contour and edge work,angle at 10 degrees. It also provides greater surface contact and is more aggressive.Best at more dramatic angle of 15-25 degrees. Characteristics: Grinding like a depressed center grinding disc and finishing like a fiber disc.Blending and finishing all in one operation and will reduce process time,lower total grinding costs. Maximum contact with work surface without loading. Rapid,aggressive stock removal on a variety of welds,castings and other metal fabrication application.Ideal disc for use on most metals and for wide range of applications such as weld seam removal,surface blending,edge grinding,and weld preparation. Consistent grinding and finishing performance. Excellent performance and efficiencies on stainless and carbon steel applications. reduce vibration and noise compared to depressed center grinding discs. Suitable for Angle Grinder.