Review on Electronics-Salon Black Nylon Round Spacer Assortment Kit for M4 Screws - OD 7mm, ID 4.1mm, L 2mm-21mm by Jeb Moorehead

I mistakenly assumed that a spacer kit would contain things that the average homeowner might one day need. (For example, changing a tire on a wheeled cart or hand truck. Or leveling lawn tractor equipment.) The spacers in this kit are minimal. Maybe you could use them if you were changing the ink cartridge in a ballpoint pen. I suppose they might come in handy if you need to embroider some little black beads onto a suit or something. I don't blame the seller. I didn't bother converting metric sizes to US inches. If you are a watchmaker or a nanotech specialist, you may need this. If you are a homeowner, just buy some different diameter PVC pipes and cut them to the right length for your project.