Polycarbonate (Lexan) is an ultra-clear plastic used for windows.  It is thicker than our window glass, but it is safer to use in models that will be handled or for models with very large windows.

Each package contain one 5.5" x 12" sheet of Clear .005 Polycarbonate.  Corresponds to 0.80" in N, 0.44" in HO, 0.32" in S, 0.24" in O, 0.12" in G