This is helpful… a lot of knowledge dropped about drag systems over at MidCurrent.
When manufacturers proclaim the virtues of their drag systems in advertisements and catalogs, they toss around terms such as “startup inertia,” and “cork to Rulon,” and “fully sealed,” often without fully explaining what these things are and why they are beneficial to anglers. If you stop to think about it, these terms raise a lot of questions about how reels are built and how they work. I set out to address these questions and more. What I learned may help you the next time you peer into that glass case at the fly shop — you’ll have a better grip on why objects with such a simple purpose vary so much in complexity … and price.