... spool regardless of numbers of inner ducts built-in. Coiling Length of C.O.D.each reel may practically coiled up ... 0°C,height 1m, 1kg hammper impact 10 times, above 9 times no brokenpassgrade7.low tem. Fall downlow temp.-30°C ... down free, no brokenpassgrade8.inner side friction≤0.50.198grade9.length shrinkable %≤31.7grade //// Corrugates Optical Ducts