I bought an adjustable drill bit at a local hardware store - either Dewalt or Bosch or Irwin - to be honest I don't remember but it was a well known brand. It was pricey for a bit but I can tell you it's fantastic. The drill itself has a slight taper, which is handy for screws. The rear cutting edge (a sprocket adjustable along the drill bit) is ideal for standard wood screws. Every screw goes in like a glove. Ok for this set - thought I'd like a few different sizes so it was a great price thought I wasn't risking anything - didn't win anything. The best thing about this set is the cost. The second best part is that the bits cut pretty well. All bits stank of oil (like gasoline) when opened. Not critical, but annoying. The smallest part was slightly bent so it could not be used. The bits aren't tapered, they're straight, which is nice, but I like the tapered bit better. The cutting sleeve is really too wide for a standard American screw, it just sticks out too far and ends up creating a wider pocket than necessary. Finally, the only piece of equipment I've bought is a standard hex shank, which you know will never turn. These are round shanks, which I was familiar with when I bought the set, but having used both, I prefer the hex shank. I wouldn't recommend them, would rather spend a little more and get a good set.