Product never used, packaging damaged during transport. Unopened product, repackaged in our warehouses, in perfect working order, warranty available. offers a diamond tile drill bit set, consisting of 6 tile drill bits, including a 6 mm yellow cemented carbide drill bit (pre-drilled) and tile drill bits of 5 mm, 1 x 6 mm, 1 x 8 mm, 1 x 10 mm and 1 x 12 mm. NOTE: The yellow drill bit (pre-drilled) can only be used as an auxiliary tool for pre-drilling and should not be used for long periods of time, otherwise it is easily damaged. To drill efficiently and beautifully, it is necessary to replace the blue bit after using the yellow bit to extend the life of the bits and improve efficiency. HOW TO USE: The procedure is to first install the yellow bit on the hand drill, tilt it at a 45-degree angle, and quickly rotate it on the surface of the material. Then, replace it with the appropriately sized blue diamond bit and easily drill the material. It is recommended to add water while drilling