PBO (Poly (p-phenylene-2, 6-benzobisoxazole)) is a rigid-rod lyotropic liquid crystal polymer developed by Japan-based Toyobo under the trade name Zylon®. PBO is a gold fiber with an initial modulus that is significantly higher than other high modulus yarns, including aramids. Among PBO’s desirable properties are high thermal stability, low creep, high chemical resistance, high cut and abrasion resistance, and excellent resistance to stretch after repeated folding. PBO is also quite flexible and has a soft hand. Less desirable is PBO’s poor resistance to both UV and visible light, which, unless a UV film is used, greatly reduces the working life of the products made with it.