I played with one of these the other day… I’m hesitant to have something so hard and angular in my pocket, but damn was it satisfying to pull cards in and out of it.
I’m a carabiner on my keychain kind of guy – always have been. When I get out of my truck, I clip the keys on my belt loop and I always know where they are. It just works for me.
Given that, I’ve gone through all sorts of carabiners for key usage. I’ve been using a Handgrey for about three years now and while expensive as hell, they are the best I’ve ever found.