The BG66UM has a 0.65mm thin gauge and the perfect balance of maximum speed, control, and durability, making it the best choice for the world's top players.. Details:. Gauge: 0.65 mm. Length: 10 m (33 ft) / 200 m (656 ft). Core: High-Intensity Nylon Multifilament. Outer: Special Braided High Polymer Nylon. Made In Japan