In reply to Erstwhile:
Looking at the size comparison, it would be pretty hard to use it by accident!
That said, I do avoid carrying accessory biners for exactly that reason: I don't want anything on my harness that's not strong enough to actually use. They say this one's rated to 4kN though, which could definitely be used in an emergency. I expect lots of people on here have abbed off weaker anchors than that (though probably not in normal circumstances!).