ALPHA Sandpaper for Concrete and Marble Polishing. Size 4". Grit: 120. Type: Hook & Loop. Qty per box: 50. Alpha® Sandpaper discs consist of a waterproof hook and loop backed material combined with a silicon carbide abrasive, which is the perfect combination for use on marbles and softer types of natural stone. Marble fabricators find Alpha® Sandpaper to be effective and durable. Tile contractors find Alpha® Sandpaper to be very adaptable to onsite work and easy to use. Restoration workers can polish wide areas quickly without difficulty. Alpha® Sandpaper resists clogging when used wet, thus extending the life of the disc. The discs can be used dry if necessary and are very durable. The hook and loop backing makes disc changes simple. Silicon Carbide is the abrasive of choice for sanding and polishing marble, travertine, terrazzo and onyx. Alpha® Sandpaper can also be used to polish glass, metal and wood. When used with our standard backer pads or the GV5000 backer pad, Alpha® Sandpaper is sure to give you the best results. For an extra high glossy finish, use the Alpha® Felt Wheel with a buffing compound to finish the polishing process.