The carbon fiber arm is the newest type of eyeglass material, which is lighter than any other on the market. Tests have shown that carbon fiber glasses of the same size are about 30% lighter than titanium frames and less than a quarter of the weight of ordinary metal glasses, making them very comfortable and light to wear.CARBON FIBER ARM - High strength, good toughness. High strength, good toughness. Carbon fiber, like diamonds, is made of carbon, so it's very tight and hard. Carbon fiber glasses are lighter than aluminum glasses, but harder than steel. They are more than 10 times stronger than iron. Carbon fiber is chemically stable, resistant to acid, alkali and salt. It is superior to other materials in anti-corrosion and can be kept intact in damp and harsh environment.PERFECT POLARIZED LENS - Bircen polarized sunglasses have a UV rating of 400, which means they block 100% of UVA and UVB radiation, without the haze and optical distortion of traditional polarized lenses. Polarized lenses optimize vision for maximum clarity and accuracy. These sunglasses are perfect for fishing, driving, playing on the beach, exercising, and any other adventure with a polarized lens.BREAKTHROUGH INNOVATION DESIGN-Bircen sunglasses metal and carbon fiber glasses arm & Wrapped design,Provides a wide field of view, windproof, sandproof, and super filtering effect.The carved carbon fiber streamlined arm design makes it more comfortable and durable without fear of slipping.30 DAYS NO REASON TO REFUND SERVICE - all Bircen customers will receive a 30 day no reason refund service. If for some reason the purchase is not satisfactory, the customer can return the product and receive a refund. You have no risk of trying and will provide you with the best service!