Dirt and mud on your bike is a badge of honor. Of course, you don't want it there for the start of your next ride.... But still!
Some fenders are plastic, some are Carbon Fiber. You want stainless mounting hardware, which costs more. The most important thing is you want fenders that fit your bike without a lot of monkeying around. Unless you're into that sort of thing!
Mark
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Bicycling is my drug of choice. Followed closely by beer.