A survey of available products, uses, and thermal resistance data for thermal insulations that use combinations of air gaps and reflective surfaces to form thermal barriers is presented. Reflective products like pipe insulation or high thermal resistance evacuated panels that are used exclusively in industrial applications are not included. A one-dimensional steady-state calculation has been developed to provide a way of discussing the R-values of refelctive assemblies and their sensitivity to properties like surface emissivity or positioning of foil surfaces in a cavity. The products considered are used in residential or commercial applications.