They worked great. Unscrew the top of the Presta, put on this product, inflate the tire to the desired amount with the Shrader Tire Inflator. You can then remove them without letting air in, or just leave them on. This product saved me a lot of time messing around with the Presta connection and my little bike emergency pump. I was skeptical after reading reviews of similar products and seeing reports that these products leaked or were too deep to press on the valve core. . There are no such problems here. Simple, simple, simple and good product. I'm not sure what I'll do with the rest of the converters as you really only need one, but I'll toss a few in my adventure bag and the rest in my tire valve box.