This review is for the 27/64" diameter of the Precision Twist 1813 drill. Most people will never need a conventional drill this long, but when you do, there are few other options. Let's say you are drilling a hole for installing a Cat5 cable and you need to go diagonally 15" through the header of a window or door frame. This drill is 18" long with 13" flutes, so it would do the job. Typically, so would an "installer" drill, which is often used for wiring jobs. But imagine you encounter something hard at 12" deep, like a nail. An installer drill would probably chip and maybe even break. However, this drill should chew through a common nail like butter. Additionally, 27/64" is often used as a tap-drill for 1/2"-20 threads. You wouldn't ordinarily need to tap anything this deep, but a long drill like this could allow you to drill a through-hole from the back side for tapping somewhere you can't reach any other way. It's not your typical drill, but indispensable for very deep-hole projects.