Specification:(1)12mm HSS 4341:Cutting Edge Diameter : 12mm / 0.47"Shank Diameter : 12mm / 0.47"Cutting Edge Length: 102mm / 4.02"Shank Length : 45mm / 1.77"Total Length : 150mm / 5.91"Material: High Speed Steel 4341Finish: Black & Gold Oxide FinishShank Type: Round ShankType: Hot RollingPackage:2 Pcs x Reduced Shank Twist Drill BitsDescriptions:1. High-speed steel tool is good for most general purpose applications, featuring a combination of hardness and toughness for wear resistance2. Reduced shank drill expand the size range capacity of a portable drill chuck. Common flute and overall length for minimal adjustment during tool changes.3. Black oxide treatment adds lubricity. Small pockets on the surface of the tool that act to hold coolant near the cutting edge.4. Design for drilling in low and medium tensile strength materials, such aluminum, iron, copper, brass and metal.5. Running in a counterclockwise direction (right-hand cut), spiral fluted tool evacuates chips up and out of the cut to reduce clogging.(2)12mm Drill Bit Stop:Color: BlackMaterial: Carbon SteelThickness: 8mm/0.3 inchInternal Diameter: 12mm/0.47 inchPackage Contents:2 x Drill Bit StopTips: It is recommended to use drill stop s with a lubricant to prevent burning of the material surface. Here is how:1) Slide correct size drill stop to desired depth on the drill bit.2) Align locking screw with land (body).3) Tighten locking screw with included wrench.4) Remove wrench before use. Great for machinery shaft instruments or on woodworking tools as a bit limit ring. No More Wrapping Tape Around Your Drill Bits!