Klein Tools 25961 2-Step Drill Bit, Double-Fluted, 7/8-Inch to 1-1/8-Inch

Either one. The 25961 has a 1/4 inch hex shank and an impact-rated shaft, so it drops straight into a 1/4 inch impact driver chuck and it will also hold in a standard three-jaw drill chuck. No adapter needed.

Yes, up to 16 gauge steel. The 25961 is rated for steel to 16 gauge, plus wood, plastic and aluminum. Typical sheet metal enclosures, junction boxes and strut are inside that range. Heavier plate past 16 gauge is beyond what this bit is rated to cut, and you would want a knockout punch for that.

A 2-step bit gives you exactly two sizes, here 7/8 and 1-1/8 inch, on a short body, 3.22 inches overall. A full multi-step unibit stacks a dozen or more steps and gets long and top-heavy, which makes it awkward inside a panel or where you have no room behind the workpiece. Pick the 2-step when you are repeatedly drilling the same two conduit sizes; pick a multi-step when you need a wide range of sizes from one tool.

No pilot hole is required. The 25961 has a split point tip that bites and starts the cut without walking when you lean on it. On thin sheet that is the difference between a clean round hole and a bit that skates across the panel face.

It carries a titanium nitride coating over a high speed steel body. The coating sheds heat, which is what kills step bits when you are drilling steel back to back, so it buys you more holes before the cutting edges dull. It does not change the sizes it cuts or the material rating.

The 25961 uses dual spiral fluting. Two flutes clear chips from both sides and the spiral helps pull the bit down through the material, so you push less and cut faster than a single-flute step bit. On aluminum and plastic it also keeps the swarf from packing into the step and galling the hole edge.

Small enough to live in a pouch. The bit measures 3.22 inches in overall height with a 1.13 inch width and depth, and weighs 0.23 pounds. The short body is the reason it works in a panel where a long unibit will not clear.