The American Optical Weld Cool No. 274 WC10 Shade 10 Welding Lens is a protective gear used in welding helmets. It measures 2" x 4-1/4" and has a shade 10 filter, which helps to protect the welder's eyes from harmful UV and IR radiation. This lens is compatible with various welding helmets and is a reliable choice for welders who prioritize safety and quality.