Open Cube Med.

The all-new performance eyewear. Specifically designed with speed-chasers and record breakers, road riders and triathletes in mind.

The Koo Open3 (or 'Open Cube') are premium sunglasses from the maker of Kask helmets. With astonishingly clear optics and solid frames that stay where you put them, these are excellent shades.

The most important aspect of any eyewear is the optical performance, so let's start there. The lens on the Koo Open Cubes is made by Carl Zeiss, and it's a very impressive bit of kit. There is not even the slightest hint of distortion right across the whole visual field.

The other notable feature about the Koo Open Cube glasses is their rotating, pivoting arms. 

Another neat feature of the Open Cubes is that the nosepiece flaps click back and forth between two positions, which means you can set them for a wide or narrow nose and then forget about them.