Wide ceramic cylinder-head, hardness 180 grit. Ceramic cylindrical heads are made of zirconium, which is known for its long-lasting durability and resistance. 60% lighter than metal cylindrical bores. Ceramic drill bits are also less static, i.e. they do not attract dust. Dimensions: - standard stem size 2,34 mm. - head width 6,60 mm - head length 13,0 mm