Amana Tool 46289 CNC 2D and 3D Carving 7 Deg Tapered Angle Ball Nose x 1/4 D x 1/8 R x 1 CH x 1/2 SHK x 4 Inch Long x 2 Flute SC ZrN Coated Router Bit Benefits of Zirconium Nitride (ZrN) Coating Creates a harder and tougher cutting edge allows for a prolonged cutting edge life and helps to prevent the build-up of material in the flutes while cutting Have the tendency to run/spin much faster than an uncoated tool Optimized flute geometry and low Total Indicated Runout (TIR) guarantees clean cuts, essentially eliminates sanding and reduces chatter (where the machine or work piece vibrates) under high chip loads (when used with low TIR spindles SPECIFICATIONS: (D) Diameter: 1/4 (R) Radius: 1/8 (a) Angle: 7 (B) Cutting Height: 1 (d) Shank: 1/2 Overall Length (L): 4 Type: Ball Nose, ZrN Flutes: 2