Actually these local fitters don't really does the work good. But your problem about the cavities can be solved. You can use slightly bigger glass film I had recently replaced glass film with the film nowadays coming with impact windows miami or you can use a sort of liquid that can seal the cavity. Apart from this the new film are serving me two ways one as a cold protector even and other they are highly sustainable so can withstand against high storms even or you can Read more about it here.
