Comfortable medium fit. Stainless steel integral hinge. Durable co-injected nylon frame. Includes hard case. 100% UV light blockage for max protection. 100% polarization kills reflected glare and reduces eye strain. Built by hand and backed for life. Every pair of Costas include a lifetime warranty. Plastic lenses are lightweight, impact- and scratch-resistant. Glass lenses have the greatest clarity and are scratch resistant.