These 40" fixed Bamboo Circulars are made of Moso bamboo which is the largest and strongest bamboo out of over 1,000 different species. Sizes US 0 (2 mm) through US 2.5 (3 mm) have the same type of memory-free cable as our RED circulars and TWIST cables! Sizes US 3 (3.25 mm) and larger have a nickel-plated, copper join that is glued and crimped to guarantee no separation. The joins are fantastic, the nylon cable is pliable and the tips swivel freely! Needle size is permanently laser imprinted on each circular.