You probably don't need to have a hundred meters of Auxiliary Rope 6mm by the meter from Fixe with you at all times, but a few meters never hurt when you're out and about on the rock or mountain. The cords can be used for prusik slings, pulleys or hourglasses, for example - or simply to attach material. For belaying, however, you should use a cord with an even higher diameter - and a real rope for climbing!