These wheels are manufactured from a natural hard felt for maximum durability and life. The smoothing wheel is coated with the same resin bonded 325 diamond that we use in our smoothing pads as a pre-polish. It provides an excellent transition from the 360, or 600 grit Crystalring® to the felt flat wheel, which when used with cerium oxide, can give you a near optical polish. A great one two combination for grinding surfaces and designs into your work without worrying about the final appearance. Both the smoothing wheel and the felt wheel are available in 4", 6", and 8" sizes to match the Crystalrings® and the DiamondBacks™ Smoothing wheels can be recoated providing they have maintained their shape. Pricing is listed above for recoats. Please send your wheel back to us and tell us which grit to recoat on your wheel.