made of HSS 4241 black chamfer drill body material: 45 steel 90 degree flute edge single chamfer High carbon heat treated hardened steel with titanium nitrate coating for superior cutting power using on steel, aluminum, plastic and wood. The drilling length can be adjusted for different situations simply by loosening and tightening the screw. Dimension: 3mm (Dia) x 60mm (L) 4mm (Dia) x 75mm (L) 5mm (Dia) x 85mm (L) 6mm (Dia) x 93mm (L) 7mm (Dia) x 10mm (L) 8mm (Dia) x 11mm (L) 10mm (Dia) x 12mm (L) Features: 1, made of HSS drill 4241 2, Black chamfer drill body: 45 steel 3, 90 degree single flute edge chamfer 4, heat treated and hardened high carbon steel with titanium nitrate coating for superior cutting power 5, Using on steel, aluminum, plastic and wood. The drilling length can be adjusted for different situations simply by loosening and tightening the screw