Simple. Choose one of our Epic Glasslines.
All our rods and blanks are designed to cast AFFMA fly lines of the designation to match our rods.
I.e - if it's a 686 rod you are enquiring about - choose a 6wt line
We do not recommend overweight fly lines (apart from our Bandit, with will cast just about anything!)
Choose a fly line designed to turnover and present the flies you are casting.
Our Glassline fly lines are designed to match our fly rods perfectly - we make them in 3, 4 5, and 6 wt only
You can see our fly line range here Epic Glasslines
We have a comprehensive article on choosing fly lines on our Blog here