Black Diamond
GridLock Screwgate

This carabiner ushered in a new wave of anti-crossload belay carabiners. The hourglass shape and gate spur provides a compartmentalized carabiner which is easy to use.

With the gate unlocked, the belayer first clips the carabiner to their harness, placing the belay loop in the first compartment. They then pull the carabiner away from their harness, forcing the loop against the gate spur. The spur will open the gate and allow the loop to drop into the second compartment. To unclip, the gate is opened twice in succession. In practice, this is a very fast and efficient motion. Interior wire gate designs can be fiddly to remove, and plastic side gate designs are bulky when not in use, and can be opened by the wire bale on some belay devices.

Note that it is possible to cross load this carabiner when linking hardware, especially using pieces with thin walls. Youtuber HardIsEasy shows this in a 2022 video on the topic.

In terms of strength, crossloading is not a huge issue when belaying off of a harness, but it can bind up a belay device or make a device more challenging to use. With mechanical devices, maintaining proper orientation increases the reliability of the catch, and reduces binding/improper loading from these two hard linked pieces of rigid equipment.

I find this model of anti-crossload belay carabiner about as easy to use as a traditional carabiner - an added convenience with no real downside if not using a Grigri or similar.

Although the BD Gridlock Screwgate is a personal favorite, I cannot recommend the inappropriate combination of the Gridlock body with a Magnetron gate even though I consider the Magnetron one of the most hassle-free auto-locking mechanisms in traditional designs.