Loon Outodoors Line Up Kit- Loon Line Speed is the best line cleaner, conditioner, and UV block for fly lines. Period! Cleaning your fly lines will add slickness and help to fill in imperfections while at the same time protecting lines from the sunr. Unlike most line cleaners, Line Speed doesn't leave a sticky, dirt collecting residue. Apply to the pads of the Line Cleaning Tool and let it sit overnight.