Soledi 15Pcs Diamond Drill Bits Coated Core Hole Saw Set Extractor Remover Tools Size(Diameter): 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 28mm, 30mm, 35mm, 40mm, 50mm. Attention: Please keep the speed in 800-1000 per minute, keep adding water to keep the drill cool, strictly prohibit from dry drilling! Applicable Industry: Suitable for Stone, Tiles, Ceramics, Glass and Granite, etc Processing Packing Includes: 15pcs * Diamond Coated Drill Bit MONEY BACK GUARANTEE! In Soledi, we hope you will love our products. If you have any dissatisfaction, please connect us freely. We will try our best to solve the problem even offering a 100% Money Back Guarantee! Its THAT simple!