 They are available in various thicknesses, from 100 micrometer (or 4 mils minimum 2 ply) through to 525 micrometers + (21 mils).The film thickness is selected for level of protection desired and the dimensions of the glass pane.Manufacturers recommend 100 micrometer film (2 ply) for glass up to 3 mm (1/8 in) and 175 micrometer film for glass over 6 mm (1/4 in).