These Diamond Wire hollow Drillsbits are perfect for your Hobby drill, Mini drill or Dermal drill .They are a great addition to any bead kit and can be used for opening up holes when bead stringing. Diamond drill bits machined perfectly straight Diamond tipped drill bit with a diamond coated end Use for drilling gem stones as stone drills, drilling beads, drilling pebbles, drilling glass, drilling jewels etc. A great jewelery making tool and Dermal accessory. These diamond drill bits should be run at 7000 - 10,000 RPM,this is approximately the slowest speed on your Dermal. Start the hole by tilting the diamond drill and then gradually moving the diamond drill to the vertical position once the hole has been started. Always use the diamond wire hollow drillswith water (and washing up liquid optional) and use gentle pressure throughout. Repeatedly moving the drill up and down enables the water to circulate and removes excess debris. Length 35mm,45mm and 65mm