Fast easy drilling of clean holes, especially in salt treated utility poles. Made from hardened alloy steel for added toughness. The self feeding threaded screw point draws the bit completely through the wood. No need to push the bit while drilling. Over center flute for evacuating chips. 7/16″ hex shank with easy to fit quick change groove for Impact Drivers.Sizes:All have 7/16″ Hex Shank Size and 15″ Twist Length:70PT-11/16: 11/16″ Diameter, 24″ Overall Length71PT-11/16: 11/16″ Diameter, 30″ Overall Length70PT-13/16: 13/16″ Diameter, 24″ Overall Length71PT-13/16: 13/16″ Diameter, 30″ Overall Length70PT-15/16: 15/16″ Diameter, 24″ Overall Length71PT-15/16: 15/16″ Diameter, 30″ Overall Length