These are made from a single piece of High Speed Steel, ground with a very fine edge.
They are only suitable for non abrasive materials, but will give a superior finish in soft timbers.
Generally HSS cutters are slightly less expensive than their TC g
Specification
D=1/4 inch
D=6.3 mm
C=16 mm
OL=48 mm
Shank Diameter=1/4 inch