We finally found one that is thin and light enough for me to wear! I have a problem with my Vagus nerve and I get sweaty, anxious and start to faint if much pressure is put on my neck or the nerves around it.
We found a lovely little thin leather collar, sold as a wrapped bracelet. Bitty little metal studs on it. It buckles in back. Cute as can be, but I don't wear it all the time. It doesn't have a D or O ring on it, just a buckle. We have me wear it when it feels right.