Lens Technology (STG-BG) The "STG-BG" combination is one of Maui Jim’s most premium optical configurations. SuperThin Glass (STG): These lenses provide the highest possible clarity. According to Maui Jim, they are 20% to 32% thinner and lighter than standard glass, offering superior scratch and solvent resistance. Bi-Gradient Mirror (BG): This proprietary coating is darker at the top and bottom of the lens. It effectively "squints for you" by blocking the harshest light from above (the sun) and below (reflections from water or pavement), while remaining clearer in the middle for a natural view. PolarizedPlus2®: Like all Maui Jim sunglasses, these include patented technology that eliminates 99.9% of glare and blocks 100% of harmful UV rays while enhancing colors. The "STG-BG" designation indicates the use of SuperThin Glass (STG) lenses with a Bi-Gradient (BG) mirror coating.