Drennan Supplex Fluorocarbon.
Supplex Fluorocarbon is available in no less than 12 accurate diameters and breaking strains, from 0.075mm (0.9lb) right up to 0.30mm (10lb). As it is made from 100% fluorocarbon, it is exceptionally abrasion resistant, sinks well and doesnt degrade in sunlight like standard mono can. It also has a very similar refractive index to water, making it almost invisible in clear water. Fluorocarbon is also less prone to spinning up on the retrieve compared to standard mono, making it a great choice for when you are continually casting out and reeling in.