I saw these on Amazon.com, they are called Tagnabbit. They have a swivel between the smaller loop and the larger loop. I didn't realize that the metal they were made from was apparently "pot" metal, because they fell apart in less than 2 weeks! I lost all my dogs tags, and am having to go to the effort of repurchasing the tags.
The greyhound tags are not costly, but just getting the adoption group to answer their email and/or phone messages has been problematic.
So, my warning is "Do not trust TAGNABBIT!