What is VLT? VLT stands for Visible Light Transmitted and is the percentage of visible light transmitted through the glass when the sun shines at right angles to the surface of the glass. Our darkest auto films are 5% VLT, and are commonly referred to as Limo film. Our lightest films are 70% VLT and do an excellent job of blocking UV rays but allow much more light to penetrate the glass. Clear films, Blackout films, and Whiteout films do not carry a VLT rating.