I just got some from a brand called Gonex on Amazon. They have a carabiner design and work great!
Those straps and rings would be okay for light & basic swinging work (i.e. front uprise, back uprise, kip muscle ups, etc.) and for slow controlled/static strength work (dips, pull ups, planche, levers, iron cross, maltese, inverted cross, etc.), but will not be okay for any movements that require strong kipping or powerful gymnastic swinging movements.
If you're looking to do very advanced swinging/dynamic movements on the rings, you need to get a professional ring set up to practice those movements safely.
However, I think these style of rings are probably the best suited for what you're looking for (assuming that you're doing basic swings/kips & strength & static work):
These rings have straps that have no cam buckle and these are quick and easy to adjust and match the height to each other and they're a lot safer than cam buckle strapped rings. The total weight capacity they have is 1100lbs so you're gonna be pretty safe unless you do some crazy olympic level swinging on the rings (which, again, you need to go to a professional facility or have a professional set up for that stuff). They're a bit more expensive than regular cam buckle rings, but IMO, they're worth every penny. Best of lucK!