The R-series is available in two mirror sizes to fit drop bar bikes, a 35mm and a 50mm diameter. They both provide a very similar view but the smaller mirror is more challenging to use, a tradeoff for the sake of minimal form. We consider the R35 our "pro" (vanity) mirror and the R50 our everyday touring model.
Designed to complement a modern drop bar bicycle. Not compatible with extreme bar geometries or positions. Some Enve bars and others without standard bar plugs also may not work. Email photos of your setup if you have any questions.