Updated review (2/11/2021) Added a photo of my metal screw size chart I made to show how well they work with metal parts. I didn't try to check the two smallest holes as I would need a tool to help with very small details. As you can see, 3mm, 2.5mm and 2mm fit perfectly. They didn't have to be glued. Last review They have nothing special. A very basic bit set that I use on Gundam plastic models to add metal detail. I previously bought a pin vise with a bunch of bits that weren't marked for size. They worked just as well, but color-coding by size is a lot easier than comparing drill bit diameter to part diameter. I don't think all products can be rated 5/5 unless they are free, so that's 4/5 stars for me.