This document is a guide to the design and manufacture of transformers and inductors for use in sophisticated systems such as manned space vehicles, satellites, missiles, and undersea telephone systems where high reliability is imperative because of the impossibility or high cost of replacement. Such components are usually made for a particular circuit application in small lots and at irregular intervals with consequent higher unit costs. This document describes the types of tests and methods of inspection of materials and workmanship to ensure reliable transformers and inductors for use in demanding applications or inaccessible systems.