For the price this is a great tool for a small job. Don't buy this expecting to use it again and again, it's just not going to happen. But if you only need a few holes or just one, this is for you. I bought two and used one to practice on a piece of glass. It took me about 15 minutes to poke a hole in my 20 gallon tank, but I took my time. After the 3rd hole the bit got really slow and I'm not sure I would use it again if I didn't have to.
So the hole saw shank is round on one side instead of flat. By using a rounded shank, the drill slips when drilling. I bought this hole saw to drill 4 holes in a granite/composite sink. The bit gets very hot, so be sure to use water. In addition, the chrome coating on the bit came off immediately. If you only need to drill a few holes, this is for you as a homeowner. The holes he cut were very good with no torn edges. Stay away from it like a pro as it is easy to use.
It only took a few minutes (literally about 120 seconds) to grind each hole in a 3/16 inch aquarium glass. hole saw and put a piece of tape on the glass behind my cut to reduce the tear on the back. I started my cut at a very slow speed, at a slight angle, and then smoothed out my approach when the saw bit and stopped. Hike. I made 4 holes with no noticeable reduction in cutting ability. I didn't break any glass. I assume I can get 10 more holes with this saw.