Produced from GCr15 bearing steel. Includes: 3 – 6, 6 – 8, 8 – 11, 11 – 14, 14 – 18 and 18 – 25mm. Drills: 2 – 9.3mm, made from HSS 4241 and black oxide coated. Produced from GCr15 bearing steel. Includes: 3 – 6, 6 – 8, 8 – 11, 11 – 14, 14 – 18 and 18 – 25mm. Drills: 2 – 9.3mm, made from HSS 4241 and black oxide coated.