I think Miles saidthat he uses 2 or 3mm marine grade parachute cord -- might be worth search the forum. I think one of the American spearos (Bill McIntyre?) mentioned using Dyneema. They both shoot huge fish though. Might be best to ask Spaghetti, as he is our "resident Italian spearo" - and will know what the locals use. (Anything on the Omer website?).