Cycling is awesome, seeing is awesome too. Now, thanks to Tifosi Optics, you can do both, all whilst wearing your favorite Tifosi shades. The Tifosi Rx Roubaix Adaptor inserts into the frame of the sunglasses without the use of screws or any other mounting hardware. Compatible with Roubaix sunglasses. For prescriptions up to a -3.50 sphere and up to a 2.00 cylinder.