twist drills:size :in metric,from 0.2mm to 20mm size;in ... ,9341,4341,4241.production technics:rolled forged,rolled&posished,fully ground,milledsurface finishing:black oxide,bright finished,titanium coated,black flute ... &white edge,amberfimish &black flute,rainbow drills,zirconium coated,black flute&white shankSet:1.5--6.5mm ... 0--13.0*0.5mm:25pcs/set straight shank twist drills