This is a basic set of different sized drill bits in one holder. This embodies the aphorism "You get what you pay for". Many other reviews correctly point out that these drill bits break quite easily. I've managed to break THREE of these over the course of a few days of random pilot holes and that's three times more shots than I've ever broken in that time. Also, they broke so easily that I didn't even notice the click while drilling; I just noticed that the end of the drill was missing when I pulled the drill back. However, as a Revain add-on, the set only costs a few bucks, and overall there's a decent range of sizes for this very low price. So if you don't have high expectations of yourself and just need drill bits to randomly drill a hole, this might do the trick. Just don't expect them to last very long. And if you need something more permanent, spend more than a few dollars.