[MATERIAL]- Diamond coated high speed steel(HSS) is made by spiral technology, has both toughness and hardness, is not easy to break. The drill bit is sharp, and is easy for chip removal. [APPLICABLE MACHINE]- Widely used in rotary tool such as hand drills, drill press, flex shafts, bench drill and hanging mill. [APPLICATION]- Suitable for drilling small holes on glass, metal, sea shells, jade, , marbles, stones, drywalls and son on. Due to the different hardness of the material, the effect is also different. [NOTICE]- When drilling, it is necessary to add cutting fluid in time to lubricate and cool down, which can get a better drilling hole wall, extends the service life and drilling accuracy. Shank Diameter: 1.0mm / 0.04 inch Drill bit Diameter: 1.0mm / 0.04 inch 1. Cannot be used for drilling wood. Diamond drill bit will generate a lot of heat during high-speed rotation, and the heat will burn the wood. 2. Low-speed drilling is very easy to break the drill bit or causes the diamond particles to fall off. 3. To prevent the drill from slipping, keep the exposed part of the drill bit as short as possible to enhance the strength of the drill Colour: silver Material: diamond Package Contents: 20 x Diamond Twist Drill Bits Only the above package content, other products are not included. Note: Light 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.