100% Fluorocarbon which thanks to it's light refraction index, which is very close to that of water, makes it invisible to fish. Knot strength 40% higher than all the best Fluorocarbon, unprecedented softness, ultra slim spool with band to smoothly lock the line onto the spool, natural clear colour and great for hook lengths for Coarse & Sea fishing. (50m spools) 0.185mm 7.61lb/50m