I have very similar looking ones from Xfitness, and I like them a lot. The rings aren't super smooth, but I don't mind the minor texture. Perhaps worth mentioning that mine have xfitness pressed into the rings. That might be annoying if you really want a uniform surface, but I rotate them so that my hands are not on the logo. Mine have different looking buckles, and they are great; I can't tell on the ones you linked.

https://www.amazon.com/Gymnastic-xFitness-Diameter-Enhanced-Adjustable/dp/B01CLPLOH4/ref=sr_1_3?ie=UTF8&qid=1507388009&sr=8-3&keywords=xfitness+rings

Good to know. Looks like Amazon has some decent wood options, too.

I want to use them outside, but not leave them outside. Is wood still the better option for that use case?