Aiden (6m) used these alot more than his other teethers and actually preferred them to his chainlink rings. He enjoys the colours and the different flexibility levels, and he really enjoyed chewing on them.
I really like the case that holds them. You can clean the rings at home and pop them into the diaper bag and still know that they are clean. It also makes finding them in the bag a snap, and I was able to dig them out easily as they were always together.