The Momentum Black Photochromic Clear To Grey sunglasses from Smith have been designed for mountain-biking. No need to take your glasses off to see when the sky is overcast thanks to the Photochromic Clear To Gray lens which lets 20 to 85% of the light through depending on its intensity, to adapt to any weather. An additional interchangeable clear lens is also provided for less bright conditions. You will also appreciate the hydrophobic and oleophobic coating of these lenses, so that nothing will obstruct your vision during your mountain bike rides.Designed with an ultra-light frame made from an eco-friendly Evolve material, they are extremely comfortable. The arms are non-slip with Megol inserts and the nose pieces are adjustable in 2 positions. The Momentum also has easy-to-adjust QuickFit temples for a custom fit. Finally, this model, with its half-frame design, will give you excellent peripheral vision!