Check the listing for details. 20" inch 500mm Diamond Grinding Disc Grit 60-800 Flat Lap Disk Lapidary Tools. Color: Silver, Condition: New. Listed at 199.99 USD. 20" inch 500mm Diamond Coated Flat Lap Disk Grinding Disc Grit 60-800 Product Specification: Outside diameter : 20" inch (500mm) Arbor hole : 1/2" (12.7mm) The arbor hole can be changed from 12.7 to 40mm, such as 25.4 mm(1" inch). Include a message when you check out telling me what size arbor hole you require, it’s free of charge. Thickness : 1.1-1.8 mm Grit : 60 80 100 120 150 180 240 320 400 600 800 (You can choose one grit from the variety of grits) Grit Type: Extra Coarse / Coarse/ Medium / Fine / Very Fine Diamond coating surface area : almost 97%, only one side is coated diamond Wet use recommended Suitable to grinding gemstone, jewelry, glass, rock, carving knife, etc. These diamond discs are one of the finest discs manufactured for Hobby, Lapidary, Glass applications The diameter flat lap wheels have a high density quality diamond coating. They are absolutely flat and parallel to meet the most exacting faceting requirements. Quick Tips 1. Recommended for rough and fine grinding on faceting material plus general lapidary grinding when precision is required. 2. All our flat laps wheels have a 1/2" arbor hole and are intended to be mechanically clamped to a Master Lap. 3. The laps are made with 1mm thick steel plate that has been machined true and flat. The lap is stiff enough to be used as is, but we recommend with the use of Aluminum master lap. Also Available in Grits 60, 80, 100, 120, 150, 180, 240, 320, 400, 500, 600, 800 Regular Air postage from China to Worldwide and takes 10-20 days delivery to your home We will send out your order within 1-2 days after payment has been received and cleared. Please let us know if you are looking for other accessories or hardware.