We got some of those. They do work .. but for indoor cats sometimes they work TOO good.
If you have a cat tree, expect that they will take a fall or 4. It's kinda sad, and dangerous really. We did it once, never again. Not worth a broken leg, or worse.
Now we just trim their claws with the nippers .. so they don't have dagger feet that get hung in stuff when they walk across it .. but they can still grip enough to climb the trees.