This 4mm Compression is a hard to find tool.  It is purpose-built for slotting plywood and creating wishbone pockets for flat-pack joinery. This bit is made from high quality solid Japanese carbide and is DLC (Diamond-Like Carbon) coated.
 
Shank Diameter - 0.250" (1/4")
Cut Diameter - 4mm (0.16")
Upcut Length - 0.2" (2/10")
Flute length - 3/4" (0.75")
Total Length - 2-1/2" (2.5")
Number of Flutes - 2
 
All HCT bits are designed for cutting wood, non-ferrous metal (aluminum/brass/soft metals), and synthetic/plastic-based materials like epoxy and sheet plastics. Bit performance varies with machine type, feeds/speeds set, and the stock material. 
 
Our CNC bits are made from solid Japanese carbide.