4 PIECES SET: Package includes 4 pieces sanding blocks. The 4 sanding blocks have 4 different grits: coarse(60#:120-180), medium(100#:240-320), fine(150#:400-500), super fine(220#:800-1000). Different grits suitable for different uses. HIGH QUALITY MATERIAL: These sanding blocks are made of high-quality brown corundum sandpaper and high density sponges basic, acid and alkali resistant, sturdy and durable, not easy to break. Each sanding block measures about 3.94 x 2.76 x 0.98inch, easy to grip and use. WET AND DRY AVAILABLE: Our sanding sponge blocks are not only suitable for polishing dry surface of the object, but also available for wet surface because the sponge have good water absorption, which means it can keep polishing with water. WASHABLE AND REUSABLE: These sanding blocks are washable and reusable, they are very convenient to clean after using, you can rinse them with water directly. After cleaning and drying, they can be reused. WIDELY USED: The sanding blocks are suitable for many kinds of surfaces such as wood, paint, metal, plastic or wall. You can use them to clean kitchen appliance,polishing wooden furniture, derusting metal equitment or polishing amber surface.