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Austri Alpin - Ovalock Belay Krab
(Get this price if shipping outside EU)
Brand: Austri Alpin
Almost every climbing hardware company now makes some sort of 'cross load proof' belay biner. This is Austri Alpin's and it is one of the better designs.
The plastic bar both locks the karb shut with no risk of forgetting to screw it up and then the karabiner is positioned such that it is stopped from rotating into a cross loaded position.