CGW abrasive flap disc are active grinding agent, provides cool cutting with light pressure. Special optimized resin bond offers maximum cutting capacity, strong edge stability and long life. Premium zirconia alumina grain with a poly/cotton heat treated backing. The poly/cotton combination provides low stretch and strength for the high Zirconia concentration that Z3 contains. XL requires high output angle grinders for best results. 4-1/2-inches diameter. Arbor hole size: 5/8-inches-11. Regular thickness. Grit: 40 (medium), Type 27 - depressed center flat disc. Maximum operating speed: 13300 rpm. Use for right angle grinder. Made in USA.