Review on 🔒 Universal Tire Valve Stem Caps (4 Pack) - Heavy-Duty Stem Covers | Dustproof with O Rubber Seal | Crown Style Design for All-Weather Protection | Leak-Proof Air Seal | Lightweight in Golden Yellow by Dustin Barry

These are cool little novelties that can be put on valve stems. The crowns themselves are plastic, but the threads appear to be aluminum. I've had them for about a month and a half now (I think) and haven't had any issues and they're all still in place. I even added air and they held up great when taken off.