Ceramic cone-tip, hardness 150 grit. Ceramic cork tips are made of zirconium, which is known for its long-lasting durability and resistance. 60% lighter than metal cylindrical drill bits. Ceramic drill bits are also less static, i.e. they do not attract dust. Dimensions: - standard stem size 2,34 mm. - head width 1,6 mm - head length 7 mm