Fly-fishing is a hobby that exposes materials to a lot of wear and tear. Even the best fibreglass rod, the strongest line, and the highest grade fishing reel reach their limits, sooner or later. The tugging of fish, the weaving of the rod, and the impact of transport will affect your fishing gear, year after year. And spare spools, too, can become damaged from intensive use over the course of time. The integrated drag, in particular, will gradually lose its retarding force. Then, casting and rewinding the line can become less precise than you are used to. So, you should always have a fishing reel with a spare spool with you every time you head for the water.