Review on 🔵 Inch Deep Conduit Knockouts with Round Design by Farhad Cantu

I'm dealing with a duct about 1" above the drywall, so I need a flat box that can be installed without a frame. It's not like this. There are no installation instructions, but I'm fairly familiar with various types of old work boxes, so I figured I could get these to work. Apparently not - after screwing in the screw on the back as in the picture and carefully aligning the box with the bracket on the ceiling (spikes down) I tightened the nut only to find the box spinning instead getting caught on the drywall. In the end, I gave up, stuck a 1x4 bar in the hole, screwed it to the drywall with self-tapping screws, and attached an ordinary pancake box to it. It worked way better than that.