Step drill bit set HSS TiAIN spiral fluted in sizes 0/9, 1, 2 in ABS plastic case - 3 pieces. Highlights and details: 4.0 - 12.0 mm / 4.0 - 20.0 mm / 4.0 - 30.0 mm. The deeply ground and spiral-shaped flute ensures absolute smooth operation and high cutting performance. In particular, non-breaking chips are cleanly removed, similar to a spiral drill bit. This reduces the formation of built-up edges and cold welds on the cutting edges. The cone shape facilitates retraction when drilling through sheets.