It's up to you on what size thread you use I use both for light lines I use 8 for 5 and over I use 6. It's totally up to the person who is making the leaders on what they want to use try differnt things and see what works best for you. As I said in another post about F leaders is there have been tons of people making them here in the past few years and who can sell you one pretty cheap if you ask or some as I have in the past have given them away just for people to try and then I've had more come back to buy from me but. Now I just mainly make them for me and my friend unless someone really wants them bad then I'd start making them again. I also make toothy critter leaders( muskie pike) if you want that Info e-mail me Later Matt if e-mailing put Furled leader in subject.

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To each there own !