I have had to drill through metal for several projects and my standard drill set was not up to the task. I was a little concerned that they would somehow not work based on various reviews. I shouldn't have worried. I first drilled out a steel bolt on a broken bike - it worked and I was able to drill a hole for a new bolt. I drilled through the steel roof and through the support beam underneath to secure the chimney cap. I drilled 20 holes in a steel cart (driven by an ATV) so we can use guy ropes on it, and I drilled a thick steel hook that goes over the roof top (to hold the ladder on the roof). add a screw. to keep it in place. In each case, I used a 3-in-1 oil to lubricate the holes as I went along. I couldn't be happier with the purchase. It was worth every penny! I love fixing things and these pieces made me happy!