Hammer drill bits S4L, SDS-max 38x520mm. SDS-Max S4L drill bits have extremely long lifetime in concrete and reinforced concrete. Even more accurate drilled holes: Optimised drill bit flute surface. Special surface treatment of the flute: Stronger surface compaction, Consistently smooth surface, Longer lifetime due to less friction, Faster drilling dust removal. Inductive brazing and hardening technology: Hardening in two steps (1. High-temperature brazing of the drilling head, 2. Hardening/annealing). Different hardness of head and flute, optimised for every drilling diameter