Sanding sponges - sponge layer prevents hot spots from uneven pressure from your fingers, contours beautifully to curves. Smooth and shape flat or curved surfaces with these convenient 4.5 x 5.5 inch sanding sponges. Suitable for all metal types including platinum, these sponges can be used wet or dry and can be folded or trimmed to fit into tight areas. Made of durable foam rubber that has been permanently bonded with aluminum oxide abrasive. This 5 pc assortment contains one each of the following grits: 100, 180, 220, 280 and 400.