5 inch Surface Conditioning Discs feature non-woven fiber infused with aluminum oxide grains adhered to a Hook & Loop backing for ease of removal and attachment. Surface Conditioning discs offer a flexibility and give during use which allows them to conform well on irregular or contoured surfaces. Additionally, due to surface conditioning discs porous nature, they allow airflow during use and thus can be used on heat-sensitive metal for polishing, grinding, blending, finishing and deburring. 5 inch surface conditioning discs with H&L back are perfect for use on steel as well as stainless steel and come in 3 variations of coarseness: Fine - Blue, Medium - Maroon/Red, and Coarse - Brown