The opening is polished and the staples are firmly attached. The Grinding Block is made of rubber,hand-held shape, moderate hardness, elastic, comfortable grip. Hand Sanding Block can self-adhesive flocking sandpaper, wool wheel, water-grinding film, sponge wheel used for grinding and polishing artificial stone, furniture, wood products, metal, automobile, etc. Material: Rubber Size: 5 inch Colour: Orange Type: A Package Contents: 2 x Hand Grinding Block Polishing Tools Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.