Mildly Interesting

For anyone wondering, belay carbiners typically lock in some manner but those used on quickdraws for anchors and removable protection (nuts, cams, etc.) typically don't.

A carbiner is strongest when its gate is closed, which is why load rated ones will have not only a gate closed rating (the highest, usually 20-22 kN or even more for steelies), a gate open, and also a lateral load rating. Your belay carbiner, that is the one clipped to your harness and is keeping you affixed to the rope so you don't hit the deck, is typically not redundant. It absolutely, positively, cannot fail. This is typically the biggest, meanest, strongest 'biner you own and will also be a locking one. You do not want brushing up against things, knocking against it, etc. to cause it to come open. You don't want it to be open if it suddenly experiences a shock load, i.e. you fall off the wall, or conversely on your belayer's end if it needs to bear the load of you falling off the wall. And you don't want it coming unclipped and lost when you're halfway up, because that's how you die.

Meanwhile, the 'biners on your anchors and protection theoretically have some redundancy, i.e. you should be clipped to more than one point along your route with more than one anchor and carbiner. But you need to be able to clip and unclip these readily, because you may well be doing so with one hand while you're dangling from your fingernails with the other. Thus they do not lock, and you can clip them to something by just slapping the gate against it.

Your keychain says "not for climbing use" on it. My keychain says ~~Desert Eagle .50~~ Petzl Angie S, 20 kN gate closed, 9 kN gate open, and 7 kN laterally.