Black Diamond Micro Stoppers are ultra-thin protection for aid climbing and thin trad lines. Copper-infiltrated steel heads fight shearing better than solid copper but are soft enough to prevent breaking the rock. The heads are swaged onto the cables, providing a more durable attachment than soldering. With Micro Stoppers you"ll be able to sew up the thinnest cracks, even if you can"t get your fingers in them. *Sizes 1 and 2 are meant for aid climbing only. Product FeaturesStrength: [1] 2kN, [2] 3kN, [3] 5kN, [4/5] 6kN, [6] 8kN Material: Aluminum Weight: [1] 4g, [2] 7g, [3] 10g, [4] 13g, [5] 15g, [6] 21gWarranty: 1 year