A #2 in either reel fits a 4wt line and backing perfectly. The GPX does everything well. I use SA's Mastery Trout 4wt when using tiny drys and 6X tippet for spooky trout. Most of tne time I use 4wt GPX with a Sage ZXL rod, and hand tied leaders. It'll turn over a woly bugger at any distance, and lay a #16 elk hair caddis down gently. Good stuff
