Cairn Sunglasses Iron 187 Scarlet Midnight Flash Grey Photochromic. Introducing the Cairn Iron sunglasses, designed specifically for altitude use in mountainous environments. These sunglasses feature a photochromic lens that adjusts from Category 2 to 4, providing excellent protection in varying light conditions. The arms are detachable, allowing you to use the supplied strap, while the foam padding around the eyes ensures comfort and extra protection against the elements. Unisex in design, the Cairn Iron sunglasses offer both style and functionality, and they are currently available online at a big discount from the recommended retail price (RRP), making them a fantastic deal for outdoor adventurers.