Review on Premium Presta Valve Adapters and Stem Caps Combo - FineGood 20 pcs Set for Bike Tire Inflation, Presta to Schrader Conversion, with 10 pcs Dust Caps by Shaun Robinson

As another reviewer mentioned, the adapters appear to work well, but the caps are really problematic. If you bought this set, like I did, you bought it for the caps versus the cheaper sets that don't include the caps. The problem with these caps is the machining (and I use that word a lot) of the threads in the caps. abominable. Some caps are so loose that they can be screwed on but removed immediately without even unscrewing them. All have mangled threads. If you've ever ruined the threads of a nut or bolt by criss-crossing it and then trying to re-tighten it, you know it just doesn't work right and tries to re-thread it every time afterwards. The threads of these covers are basically the same as from the factory. I looked under the microscope at low magnification and saw that there were "mountains" with "valleys" engraved right in the middle. One strand is pureed and cut into 2 smaller strands. Also, to keep things interesting, these caps are brimming with burrs and little bits of metal that never seem to go away. I've tried gently screwing and unscrewing the cap, hoping the threads will eventually align and the metal bits will all shake out, but it's like an endless burr and bit factory. This is tolerable blood that would make any machinist or auto mechanic shudder. One of the black adapters had the anodization already scraped off, leaving big, ugly, shiny marks. Luckily I liked the gray ones better for my bike. I could try using the caps and see how it goes but I suspect they will come loose after a few rides. I'll probably just buy the ugly but reliable Schrader plastic caps.