These are our "KLINGSPOR GOLD" sheets. They are Aluminum Oxide with a very flexible cotton backing. This material works great on contoured workpieces such as scissor handles, dental instruments, etc. Our "gold" material is best suited for stainless steel and high alloys, but can also be used on other ferrous metals and non-ferrous metals. This material is also used in wood sanding and is often called "A Woodturners Dream Paper". This material has a special gold-colored top coating to aid in cooling and to resist loading.