Performance requirements and methods of test established by the National Bureau of Standards for metallic window foil are described. Metallic window foils covered by this standard are classified as foil that is precoated with adhesive and foil that is not precoated. The document also provides requirements for electrical resistance and foil breakage, outlines test methods, and describes test equipment consisting of glass panels, glass cutters, a break fixture, an ohmmeter, and adhesive. Procedures for an electrical resistance test and a foil breakage test are given. Equipment which can meet requirements of the document is of superior quality and is suited to the needs of the user. Purchasers can use the test methods to determine firsthand whether a particular equipment item meets the requirements of the standard, or they may have the tests conducted by a qualified testing laboratory. Diagrams of a break fixture are provided.