Lincoln Electric K3540-3 Viking 3250D FGS Auto Darkening Welding Helmet - BlackLincoln Electrics VIKING 3250D FGS auto darkening welding helmet (K3540 3) is built for welders who want a clear, controlled view of the work while maintaining comfort through long shifts. It uses 4C Lens Technology and a 1 1 1 1 optical clarity rating to reduce distortion and help maintain shade consistency, paired with a 12. 5 sq. in. auto darkening display for a wider process view. For added awareness and protection, it includes Shade 5 side