This specification covers the general requirements for electromagnetic relays with main contact ratings of 5 amperes and above at 270 V dc and auxiliary contacts and coil voltage as specified (see 3.1) for use in electrical applications. Relays covered by this specification are capable of meeting the electrical and environmental requirements when mounted directly to the structure of aircraft, missile,spacecraft, ship, and other primary vehicles or in ground support and shipboard equipment as well as when used within other subsystems such as electrical load management centers or power controllers.These relays have reliability ratings established on the basis of tests performed at +85°C or highest rated temperature (see 3.1) under the rated load conditions specified herein at a 90 percent nfidence level for qualification and 60 percent confidence level for maintenance of qualification.