i thought it was red for the fish striking factor? how can it be invisible?? maybe im wrong.....but they make many neon lines that are made for visiblity.....gold.....neon green.....hot pink.......also berkly transition......it turns gold with the sunlight.....but its flourocarbon....and is supposta be REALLY close to invisible.....the normal berkly vanish does dissappear.....i saw them using transition on TV.......and it works.....above the water its gold...and below its invisible....looked like it worked to me....and when they would cast the burried line under what they casted was clear...then after a few seconds turned gold with hte light.........looks neat....never used the cajun.....read about it in....cabelas i think.....could sworn they said its red for fish striking blood..........