Trout Magnet S.O.S. Fishing Line S.O.S. is a copolymer line that is soft and easy to cast, it has excellent stretch and abrasion characteristics that make it the perfect line for light-line fishing. It is hard to be a successful fisherman without using the right line. The problem is - it is difficult to find a light line with the right color and the right strength. Using the proper line will make a difference in the amount of fish you catch. S.O.S. lines are the strongest lines on the market when comparring lines of similar diameters.