Hss twist drill bit set this hss twist drill bit set contains 6 drill bits each made out of hss which is high speed steel is a form of tool steel which is hard and much more resistant to heat than high carbon steel they can be used to drill metal hardwood and most other materials at greater cutting speeds making these drill bits highly durable finished in black drill bit set black finish size 2 3 4 5 6 mm hss rolson warranty 6pc