Chastity device discussions and reviews discussion

I’ve got a submissive who is keen to experiment with chastity. He mentions he’s attempted using a device featuring a 52mm ring, but struggles to fit it.

Does anyone know of an affordable option that offers a larger ring? Are there even models available?

He prefers not to commit too much money right now since he is just testing the waters and isn’t sure if this lifestyle suits him yet.

What is his circumference? It might sound like a basic question, but does he understand how to correctly position the ring?