The Tifosi Optics Escalate S. F. Photochromic Sunglasses pair innovative lens technologies with versatile interchangeable frames for cyclists and runners. Each pair comes with a full frame with two interchangeable lenses and two frameless Shield frames with fixed lenses. The Shield frames feel best during high endurance workouts, while the full frame has a more casual look off the bike. A simple clip lets you interchange each frame in seconds, and the padded temples and nose pads adjust for a personalized fit. A photochromic Fototec treatment helps each lens adjust automatically to the ambient light around you. Tifosi Optics coated the scratch resistant lenses with a hydrophilic coating to repel water, oil, and dirt. Proposition 65 Warning for California Consumers: This product contains chemicals known to the State of California to cause cancer andor birth defects or other reproductive harm.