A polarizing film is a sheet of stretched polymer with a dye that absorbs light vibrating in one direction. One film does the job on paper. In practice, a single film warps under heat, delaminates at the edge, and lets a measurable amount of glare leak through at low sun angles.
Our lens stacks nine thinner films, each at a marginally different tension. The result is a filter that stays flat across the whole lens, holds its polarizing axis in a hot car, and cuts reflected light to below three percent at every angle we can measure.
It costs more to make. It also means the pair you buy in year one looks the same in year five.