The BlueWater ropes 5mm Titan Cord is constructed from Dyneema fiber and nylon which makes it strong and light. It is available in 6m (~20ft), 25m (82ft) and 50m (164ft) lengths. It should be noted that the true diameter is actually 5.5mm.
Keep in mind that thin cord like this has its limitations and concerns. A triple fishermans knot (required), it’s very hard to cut even with a knife, and many people have concerns about spectra cords in general.
