Circular connectors are designed with a circular interface. The connectors usually consist of pins with exposed terminals and sockets that receive the pins, and are used in a wide variety of applications including transmitting various signals and power. Circular connectors are available in various numbers of cores, contact shapes, dielectric strengths and shell sizes for use according to operating environment. Additional functionalities may include single-action engaging/disengaging, highly waterproof characteristics that allow the connector to be submerged during use, locking mechanism to prevent accidental disengaging, etc. Pin-to-socket coupling styles include threaded types that are threaded on the exterior and twisted in, bayonet and reverse-bayonet that can be engaged/disengaged in a single action, twist-lock where the pin-side is twisted to lock, and more. Circular connector specifications range from 1 to 74 cores, allowable current of 0.5 to 350 A, allowable voltage of 12 to 6,600 V DC, etc.