You've got a 3/8-inch chuck and you need to drill a 27/64-inch hole — that's not a standard size, it won't fit a reduced shank in some cases, and a 1/2-inch chuck isn't on every drill. A reduced-shank bit solves the problem without swapping chucks or guessing at step drillers. 27/64-inch titanium nitride coated reduced shank drill bit. The shank steps down from 1/2-inch to fit a standard 3/8-inch chuck — no adapter needed. Titanium nitride coating adds surface hardness and extends cutting life in steel, wood, and light masonry. 118-degree conventional point for general-purpose starting — walks less than a split point on curved surfaces and handles multiple materials without switching bits. Standard in the bit cases of electricians and plumbers across northeast Nebraska and northwest Iowa — Stocked at Crofton Lumber and Akron Lumber.