I’ve seen belay biners crossloaded more times than I can count. That is, when the belayer is lowering the climber, the belay biner spins unexpectedly and the climber is essentially lowered from a weak point of the biner. Biners are designed to take a load vertically against its axis points, not horizontally against its bar stock or against the gate. Cross loading just happens, and up to this point, there have been few solutions that have caught on.

The new Black Diamond Gridlock Screwgate($19.95, 2.7 oz) eliminates cross-loading due to its tear drop shape and unique closure. Additionally, when in use the belay device is separated by the belay loop by a pin.

http://www.blackdiamondequipment.com/en-us