Forgot to mention about fighter line sets. I use Spectra fishing line exclusively since the braid is a bit courser than kite grade Spectra. This adds some “bite” which is ideal for fighters. And just like on sport kites, Spectra is very durable and the lack of stretch produces a crisp response.
My preferred brand is PowerPro in the 30# test (0.011” Dia). While that test is overkill for most fighters, anything lighter proved too thin and dug into my fingers – OUCH! Anyhow, should be available at most sporting good stores. What I did was buy a 150 yard spool and then split it with a buddy. And try to get the Hi-Vis Yellow or Red colors...the typical Moss Green camouflages with the grass. Here are the specs: http://www.alltackle.com/power_pro.htm
Oh yeah, here is one last line tip: Tie a simple knot into the line about 20 feet from the spool end. When flying, this knot will serve as a “speed bump” letting you know "the end of the line" is near. Otherwise, very easy to be in fast dive and then discover you have no excess line available to change course. Lawn dart city!