Trend Snappy 6.35mm x 12.7mm TCT Counterbore - to recess screws for plugging
"12/7mm diameter TCT counterbore to drill precision recess to hide screws below the surface when used with matching plug cutter.
Ideal for screws up to 12 gauge Imperial sizes."

Specification
D=1/2 inch
D=12.7 mm
D2=1/4 inch
D2=6.35 mm
C=8 mm
Shank Diameter=1/4 inch hex