They are shown with knurled threads that attach to the valve stem. When they arrived I was happy to see that they actually have a hex bolt that can be tightened with a wrench. I used to be the "finger tight" type and always felt like I wasn't tightening them tight enough - on the ones that arrived I could tighten them with a wrench and gently tighten them where I wanted. So far so good, they were installed within a couple of weeks with no sign of a leak. I haven't taken long trips with them, only short trips, so I'll update this review if anything changes or if they don't work properly. I use them on my RV, front tires. Thank you for reading.