Product details:

Best performance with drilling into hardened, tempered alloy steel, nodular graphite malleable cast iron, and stainless. It is suitable for drilling to a depth up to four times the diameter of the drill. The 209CO series has a type N flute form, with a regular helix angle (21 to 34 degrees). The gold oxide is a low temperature heat treatment which reduces grinding stress within the tool, and has an appealing, easy-to-identify gold color. Gold oxide is commonly used to identify cobalt steel tools. Spiral flutes act as a passageway for chip extraction from the hole and for coolant to enter the hole.