Review on 🔩 Yuerseak 7 Piece Drilling Concrete Alloy Set - Ultra-Durable & Stylish Black Design by Eric Mueller

Tl;dr: They work great. They're metric, but they pierce through hardened steel well and are cheap enough that you won't feel bad after blowing one of them. I bought this set of bits along with some pure carbide twist drills. The four twist drill bits I bought cost over $100 and I ended up breaking one of the expensive drill bits while drilling hard steel (S35VN hardened to 60 HRC). I ended up with them and they dulled, but consider this set of bits did the job and cost less than half the price of a solid carbide twist drill. You can buy multiple packs of these for the same price as a drill doctor to fix more expensive bits. There is a downside to all of this. They're actually measured in millimeters, so they don't match fractions of an inch perfectly (the packaging confirms they're metric). If you need a hole exactly 3/8 inch this is not for you. But if you're happy with a 10mm hole, then go for it. The actual sizes of these bits are 6mm, 8mm, 10mm and 12mm. Take four 6mm bits to keep them fresh when making the first few holes. You'll only get one of the larger sizes, but you'll get a few holes out of it if you go slow and use coolant.