Polyshield Reflective bubble insulation is a vapor barrier (solid, non-breathable), 95% heat reflective insulation product manufactured with encapsulated air bubbles between one or two highly reflective surfaces designed to keep out summer heat (heat gain) and hold in heat generated in the winter (heat loss), while reducing moisture condensation and blocking water vapor. The encapsulated air bubbles provide a thermal break to minimize conductive heat from moving through the material.
Polyshield single bubble foil/foil is an inexpensive variation for those looking for an economical solution, as well. It has the same 95% reflectivity as all the other variations. The foil/foil variation is most commonly used inside finished walls.