[Diamond Hole Drill Bit Size] Dry diamond core drill bits kit size included:30pc-6mm hole diameter drill bits with 1/4 Hex Shank,length is 65mm. [Dry Drilling] Design that can melt and cool the cutting during dry drilling,you can also use water as an additional coolant to extend the life of the drill bits. [Wide Application] Diamond hole saw set have wide application,you can use them to drill holes for your ceramic pots,also can use in different hard material such as:,Tile,Glass,Marble,Brick,Stone,etc. [1/4 Hex Shank] Drill bits are hex shank design that is more suitable for electric drill chuck,not easy to slip when working,improve work efficiency. [Friendly Reminder] In order to improve the service life of the drill,it is recommended to open the small moon pressure groove on the item at a 45 degree Angle during the whole high-speed process, and then slowly erect the drill to 90 degrees Please note that the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! With or without scales, they are shipped randomly and cannot be specified. Colour:Black Material:diamond Package Contents: 30 x diamond drill bits Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.