The Yale Bee Line Blue 10 mm, 800mm Whiptail stitched e2e - the official length for use with the Singing Tree Rope Wrench - the first friction cord specifically designed to wick the heat generated by rope-on-rope friction away from the knot. Kenetic energy is produced in a DbRT system particularly on a long 'run'. This energy is converted to thermal energy (heat) at the knot - if left with no place to go it will melt your rope. The Technora fibers in Yale Bee Line allow high heat tolerance without damaging the friction cord or your rope. Yale Bee Blue 10 mm has a 12-strand Vectran core covered with an extra tough sleeve of blended Technora Aramid/polyester (75%/25%).