Micro thin to maximise your spool capacity.
90% of fish are lost due to the backing being too thick, forcing line against the reel.
That's why we've made ours low diameter. Low diameter Dacron ™ braid backing with a 2 tone hi vis braid pattern. Knots easily and dries when on the spool. We use this backing for freshwater and saltwater fishing.
We also use this backing in 8' sections as indicator material when nymphing, applying Lineslik to make it float or leaving it untreated for direct line nymphing.
There's no difference in the colour options, but we use red for floating lines and green for sinking lines. It makes for easy identification of lines on reels.
Try terms like "sinking fly line"