Production of submarine telephone cable repeaters, designed to have a minimum trouble-free life of 20 years, required many new and refined manufacturing procedures. Care in the selection and training of personnel, manufacturing environment, inspection and testing were of great importance in the successful attainment of the ultimate objective. Quality of product is always important in communication systems, but the building of electronic equipment for use at the bottom of the ocean, where maintenance is impossible and replacement of apparatus is extremely expensive, required unusual manufacturing methods.