Directly from HEXIS themselves. Here is more information on the Air Egress, or bubble free feature in their films.
All about our HEX’Press liner
All our products starting with the letters HX (for example HX30000, HX190WG2, HX200WG1) bear this liner.
It is a structured liner which allows easy evacuation of the air trapped between the film and the surface. Because the immediate tack is not very sticky (which is normal), it also makes the film repositionable during installation. Applicators have calculated that this HX liner saves around 30% of their time during installation!