... 1.ISO9001:2008 2.Professional manufacturer 3.Spiral flute 4.Good quality/Competitive price 5.Bright finished ... .) Step drill bits 2.) Spiral flute 3.) Step drill, bright finished 4.)HSS steel 5.) ISO9001Step drills are ground ... .) Step drill bits 2.) Spiral flute 3.) Step drill, bright finished 4.)HSS steel 5.) ISO9001 Step drills are ... ,16,19,21,23,26,29,32,35,38mm100mm126-40mm6,11,17,23,29,30,31,32,33,34 ...