Given to a friend last Christmas. They were perfect and fitted the valve stems like a glove. A few months later my friend had to inflate his tires and couldn't get them off. Aluminum oxidized on the rod. With wd40 and wrenches I was able to remove most but couldn't move the last one. The lids were severely scratched. This is a major disadvantage of this product. When you buy them, be sure to add some rust inhibitor to the threads.