Window film shades are measured by VLT, or visual light transmission. Essentially, the VLT is the amount of light that can pass through a window film. A lower VLT (5% for example) will have less light transmission and appear darker. A higher VLT (75% for example) will have more light transmission and appear lighter. We see the average vehicle owner desires to have around a 15% overall VLT for ideal appearance without poor night time visibility. However, we advise you to choose a window film shade that correlates with your lifestyle, vehicle type, comfort level, and driving visibility preferences.