DRYGRES 4DRILL diamond drill bits are designed for use with electric drills. Hexagonal connection of drill bits with 13 mm head. The drilling depth of the DRYGRES 4DRILL is 36 mm for the diameters 6, 8 and 10 mm, and 40 mm for the diameters 12, 14 and 20 mm. All DRYGRES 4DRILL bits have a wax inside. The wax melts with the use of the drill bit and improves cooling and removal of drilling debris. When dry drilling, it is important to cool the drill bit properly, so make continuous and circular movements with the drill. This improves airflow around the drill bit. Revolutions per minute - 1000 min, Maximum drilling length - 40 mm, Number of pieces in a box - 1