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FLUOROCARBON Line from STROFT, FC1 is the 100% fluorocarbon fishing line with the highest breaking strain that has yet been tested by the EFTTA

According to the manufacturers FC1 is described as follows:

Converts to the qualities of fluorocarbon - abrasion resistance, low stretch, sensibility, casting performance, durability, visibility - preferably use STROFT FC1 as leader and tippet material. The line has been optimised for ultimate knot strength.

For the best knot strength this is the one to use but it is expensive and for most purposes I would use FC2 since it is quite a bit cheaper.

These 25m spools can be fitted with Stroft Cutting Rings to make it easier to cut lengths of tippet:

These 25m spools are compatible with the new Stroft Spools System: