This product is sponge sand, without sand dropping. It is suitable for polishing surface and polishing the outer casing of the mobile phone. It can be used repeatedly for a number of ordinary sandpaper. The inside is a sponge structure, especially suitable for grinding arcs, arcs, etc., which can be well attached to the arc surface when grinding. It can effectively avoid the non-circle phenomenon caused by ordinary sandpaper grinding._x000D_ _x000D_ Features:_x000D_ 1. Can be used repeatedly,equivalent to many ordinary sandpaper, it is practical and durable._x000D_ 2. Inner sponge structure, suitable for grinding curved surface, spherical surface, plane_x000D_ 3. Dry and wet, easy and convenient._x000D_ 4. Both pneumatic and electric polishers can be used._x000D_ 5. This product can be used to polish phone shells and paint surface._x000D_ _x000D_ Specification:_x000D_ Size: approx. 90 * 90 * 90mm / 3.5 * 3.5 * 3.5in_x000D_ Number of holes: 6 holes_x000D_ Thickness: 5mm_x000D_ Quantity: 4pcs_x000D_ Grit size: 300-400#, 1800-2000# (optional)_x000D_ _x000D_ Package list:_x000D_ 4 * Sandpaper_x000D_ _x000D_ Note: _x000D_ There are some errors in the manual measurement, thank you for understanding