Insulated units are commonly known as thermapane units or double pane glass units. Seashore Glass & Mirror provides the best quality materials to manufacture our insulated units. They are processed and constructed using four hundred degree hot butyl compound which seals the spacer material and glass together so that they do not fail. We warranty all of our insulated units from fogging for 20 years. We will replace any insulated unit free of charge for up to 20 years if this happens.