The search is very useful for the popular subjects:
And there’s also some Lovehoney guides that cover the basics -
How to Use a Cock Ring | What is a Cock Ring | Lovehoney UK
How to Use a Vibrating Cock Ring | Lovehoney Advice guides
And there’s a good podcast too:
For the vibrating ones, we prefer the ones with a broad face rather than the ears. Mrs Chimp thinks they provide more consistent stimulation, and are good for grinding positions. We tend to use them more as penis-mounted vibrators than constriction devices though, so that’s worth keeping in mind. 