I was in Traverse City, Michigan a few months ago. One of the items I ended up buying was a growler collar. Perhaps I had never been really looking, but I've never seen any of these before. I've seen some pretty funky stuff with people and their growlers. I've seen people bring in growlers that had warm beer in the bottom of them still, and I've smelled some pretty nasty growlers from several feet away when people take the cap off for the first time in weeks or months.
I've always disliked the shape of the growler. It isn't easy to wash out thoroughly and dry very easily due to its shape. I normally just use my homebrew spray spigot to wash them out and then try my best to stand it up in the dish drainer. It would always have some water in it when I would dry it though. I tried the dishwasher once and the growler exploded with the heat cycle. I'm married, so I can't go down that road again.
I thought this product has done a good enough job to warrant passing it onto others.
It is a very simple product. Just a small round disk with a threaded hole in the middle. Just wash your growler, twist the collar onto the top of the growler, and then let dry.
Has anyone seen any of these around town? If you want one you can purchase them here.