【WET AND DRY SANDING】Latex paper backing is waterproof,good flexibility,wear-resistant. 【PREMIUM MATERIAL】Premium Wet Or Dry Sandpaper Is Constructed with white fused alumina abrasive which is the purest alumina(Alumina powder content 99%),Low heat generation and high grinding efficiency, Fast and long lasting cut with a consistent scratch pattern The purple abrasive will not discolor the surface you are sanding.