The 9. 4 Climbing Rope is Black Diamond's skinniest line that's certified solely for for single use. It's a balance between lightness and durability that advanced climbers look for whether they're projecting sport or trad. Its 9. 4mm diameter is at once supple and strong to slide through carabiners without much rope drag and still take a surprising amount of falls. Since it sits on the skinnier side, this rope is a great option for the occasional alpine approach as long as the rocks are dry.