HMS carabiner with safety gate to prevent accidental cross-loading. The Smart HMS is all about safety and easy handling. The screw gate can be operated only when the safety gate is open. This prevents accidental opening as well as unintentional twisting of the carabiner in the belay loop of the climbing harness, ruling out the risk of dangerous cross-loading of the carabiner. Mammut recommends use of the Smart HMS for the Smart 2.0.