Hitachi 728035G 1/2-Inch by 6-Inch Installer/Aircraft HSS Black Gold Drill Bit (Discontinued by manufacturer) This bit is used in specialized applications because of their ability for drilling and running wires through walls, ceilings and floors Hitachi DuraCore treated products are manufactured utilizing a proprietary technologically superior to cryogenic treatment. DuraCore is not a coating, so it will never wear off or chip away Hitachi Black Gold drill bits stronger, sharper and last up to 300-Percent longer than standard Black Gold drill bits Comes with a 30-day limited warranty