Straight, Double Fluted Step Drill Bits from Klein Tools provide cleaner cutting and drilling. The aluminum titanium coating is 10 times more durable than steamed black oxide for longer bit life. 3/8-Inch hex shank is durable, and has a firm, positive grip. Laser-etched markings provide quick size identification on primary holes. This step bit has 3-hole sizes from 7/8-Inch to 1-3/8-Inch (22.2 to 34.9 mm). For more than 160 years, Klein Tools has manufactured premium-quality, professional-grade hand tools that deliver the performance, durability and precision needed to get the job done right. Our family of engineers, workers and craftsman continue to put six generations of expertise into every tool we create by using only the highest quality materials, superior workmanship, and keeping manufacturing as close to home as we can. Klein isn't just the name of our company, it's also our family name. And since we're an American company that's family-owned and family-run, you know you can count on us to be here tomorrow. Klein Tools doesn't just make great products, we make great products that stand up to the demands of the professionals who use them every day ... Since 1857.