... Zirconium Coating, Black, Coffee Color HSS Double Ended Twist Drill BitsProduct Description:HSS Twist Drill Bits, Double EndedFully Ground4341,9341,M2,M35,M42 3 ... drilling immediately.* twice as many holes as a single end drill bit.* used primarily in small machine shops and automatic body shops ... metals, steel sheet, sheet brass, sheet aluminum and plastic sheets. Double end drill bit