Most window films sold for safety or security applications will have a break-strength quoted on their product specifications or brochure. Consumers reasonably assume that this figure is indicative of performance and security. The problem is, this is not the case.
The break strength quoted in product specs and brochures is the beak strength of the raw polyester substrate used in the construction of the window film or laminate. Because the polyester used in films and laminates is often highly similar, the break strengths of the raw substrate will be similar. But this does not mean all films and laminates will perform the same once applied to glass.
There are other factors that ultimately determine performance and the ability to protect glass once applied. The entire assembly of window film or laminate has to be taken into consideration. Ultimately, performance is a factor of: quality of the adhesives, quality of the polyester and, in a true laminate, the orientation of the individual plies of polyester.