Do yoga rings come in different sizes?

I have a yoga ring at home that I bought cheaply, but I think the size is small. I bought this because it said 'S' on it.

But I'm not feeling any stimulation at all. I don't feel anything even when walking with the yoga ring on. Others say it hurts a lot when they walk in them, so I wonder if I chose the wrong size...

It's a shame that it doesn't perform its function properly, considering I paid for it even though it was cheap.