The story of carabiner evolution: on the eighth day God created various implements of climbing including carabiners. For six thousand years nothing happened. Then in the twenty-first century everyone got all crazy and started innovating. Sub-ounce biners, wiregates with just one wire, crazy stuff.
Black Diamond is one of the worst offenders in the area of biner-vation. We love their VaporLock screwgates for no-open scenarios, but we're replacing them with the Magnetron RockLock for this season's Denali slog. Reason? We don't need no stinkin' reason, but if you must have one, it's just this simple: no screwing. Now we're not against screwing in general, mind you, assuming appropriate conditions or, failing that, mutual consent between adults, in which case we are absolutely pro-screw. Ing.
More specifically, it's screwing with gloves on that we have a problem with. And screwing at altitude. In the cold, when the thing you're screwing with has frozen solid. That's a problem, right? So in those situations, no screwing will be a good thing, and the Magnetron allows you to simply squeeze one out. The gate, that is. All by yourself.
At 3.1 ounces, it's a tad heavier than the VaporLock, but we're OK with that since we really only pack a couple lockers with us on the big rock anyhow. Being able to place an anchor, clip the equallette and pinch the gate open is fabulous. That's right, we said fabulous, because you're avoiding two screws: one to open, one to close, so that's a lot of screwing saved. Now if DMM and BD could put aside their differences and make a Magnetron Revolver, we might forsake screwing forever. Again, specific to certain situations.