The Makita HSS TiN Metal Drill Bit Set 19pc is ideal for professional use as the drill bits have a titanium-nitride coating, this means that they produce minimal levels of friction and therefore reduces friction deposits, keeping the work area clean and tidy and not causing any damage or staining. The HSS construction ensures these drill bits are suitable for alloyed and non-alloyed steel. Included in this set is two 1.5mm drill bits, two 2mm drill bits, two 2.5mm drill bits, two 3mm drill bits, one 3.2mm drill bit, one 3.5mm drill bit, one 4mm drill bit, one 4.5mm drill bit, one 5mm drill bit, one 5.5mm drill bt, one 6mm drill bit, one 6.5mm drill bit, one 7mm drill bit, one 8mm drill bit, one 10mm drill bit and a split point all in a organised carry case to help keep .