Climbing set of 9 pcs. nuts made from Alu from Czech producer. How nuts work Nuts hold falls in slightly different ways, depending on the design of the nut and the nature of the crack. Nuts are "passive protection" as opposed to cams, which are "active protection" because cams expand into a crack and nuts just sit there until a downward force is applied. On a simple placement the head of the nut is too big to fit through the the crack below it. That is why all nuts have taper, or a thinner bottom and and wider top. Different amounts of taper allow more or less surface contact depending on the crack, which is the key to holding power. As the crack become more parallel or irregular, a curve design helps in two ways. First the curve creates three points of contact, which makes the nut more stable and to a certain extent allows the nut to cam into place. The second benefit of a curve is that it potentially allows more surface contact with irregular or more textured rock. All nuts have slightly different curve and taper. That's what affects its ability to hold a fall — the amount of surface contact in a given crack. Tech specs: * Size 1 - range: 10-11.8 mm, weight: 24 g, strength: 8 kN * Size 2 - range: 11-12.8 mm, weight: 25 g, strength: 8 kN * Size 3 - range: 12-13.8 mm, weight: 26 g, strength: 8 kN * Size 4 - range: 13.5-15 mm, weight: 27 g, strength: 10 kN * Size 5 - range: 15-17 mm, weight: 29 g, strength: 10 kN * Size 6 - range: 17-17.5 mm, weight: 32 g, strength: 10 kN * Size 7 - range: 19-20 mm, weight: 36 g, strength: 10 kN * Size 8 - range: 21-23 mm, weight: 43 g, strength: 12 kN * Size 9 - range: 23-24.5 mm, weight: 50 g, strength: 12 kN