Not used these, though I have seen them advertised before. At this price it might be worth a punt. You could then post a review to aid anyone thinking along the same lines.
My only reservation is the short grain, though this isn't too much of a problem with curtain rings.
A sounder way to approach it night be to laminate thin veneers around a mandrel. Or even wood around a metal core as in the examples posted by @Padster, on this forum under 'The last thing you turned'
Thanks @niall Y - I use a 'proper ring mandrel, then stainless or titanium cores as you mention on the rings I've made, these can be singular or two pieced to give an inlay type effect.
I guess some people can produce good products using this and I'm not a snob, if it works for you as they say.....
Or a more apt golfing phrase...... there's no pictures on the scorecard!