A downsized version of its bigger brother, the Flight Tracker L, the M is designed for medium-sized faces. The full-rim, low profile frame creates a modern look with an increased field of view over its predecessor. The shape fits well with helmets and the silicone backed strap keeps the goggle firmly in place, it\'s also Over the Glasses compatible. The lens uses Oakley’s tried and tested Prizm technology for razor-sharp clarity and increased depth perception.Lens: Prizm Sapphire IridiumVLT: 13% (CAT 3)Size: MediumLens Shape: ToricLensPrizm Sapphire Iridium is suited for variable to sunny conditions; the Iridium coating reduces glare from sunlight reflecting off the snow, whilst the rose tint increases definition in flatter light. Prizm technology blocks specific wavelengths of light whilst boosting others to provide maximum contrast and enhanced visibility. This greater clarity results in reduced reaction times and increased performance over a wide range of light conditions.Visual Light Transmission, VLT, refers to the amount of light that penetrates a lens. A low percentage means less light passes through and a higher percentage lets an increased amount of light through. A lens with a lower VLT rating is better for bright conditions, where as one with a higher VLT is more suited for overcast and snowy days.