ChiaoGoo fixed Bamboo Circulars are available in different lengths. They are made of Moso bamboo which is the largest and strongest bamboo out of over 1,000 different species. Sizes 2mm through 3mm have a memory-free cable. Sizes 3.25mm and larger have a nickel-plated copper join that is glued and crimped to guarantee no separation. The nylon cable is pliable and the tips swivel freely.