Electrical or fiber-optic connectors used by U.S. Department of Defense were originally developed in the 1930s for severe aeronautical and tactical service applications, and the Type "AN" (Army-Navy) series set the standard for modern military circular connectors. These connectors, and their evolutionary derivatives, are often called Military Standard, "MIL-STD", or (informally) "MIL-SPEC" or sometimes "MS" connectors. They are now used in aerospace, industrial, marine, and even automotive commercial applications.

Characteristics

Connectors usually consist of (i) a mating pair (plug and receptacle) each equipped with male (pin) or female (socket) contacts; note that at least one of the connector halves, or its contacts, should be floating to minimize mechanical stresses.

Electrical connectors

Fiber optic connectors

Additional connectors

Selection of connector alternatives that are not defined by military specifications (MIL-C or MIL-DTL) can use either designated performance specifications (MIL-PRF) issued by the Department of Defense (DoD) or by using Commercial Item Descriptions (CID) issued by the General Services Administration (GSA) pursuant to DoD 4120.24-M, or by using standards developed by nationally and internationally recognized technical, professional, and industry associations and societies, collectively referred to as "Non-Government Standards Bodies" (NGSBs). Performance Specifications: These connector specifications are intended to describe product that is essentially the same quality previously defined by familiar military specifications and built under the DoD's Qualified Manufacturer List (QML) product/supplier controlled system rather than the more-stringent Qualified Product Line (QPL) system. Commercial Item Descriptions (CID): CIDs are specifications describing products that are defined by the connector manufacturer's specification versus a military specification. These products may not be suitable for environmentally severe or critical, communication or tactical military applications; however the items may be an acceptable cost effective choice in less demanding military or commercial applications.