... Competitive price 5.Bright finished Step drill with spiral flute1.) Step drill bits 2.) Spiral flute 3.) Step drill, bright finished ... of 5mm. Also suitable for wood and plastics. *Spiral flut gives the faster drilling speed and faster dust ... of 5mm. Also suitable for wood and plastics. *Spiral flut gives the faster drilling speed and faster dust ... 15,16,17,18,19,20mm88mm11 Step drill with spiral flute