What are E/O cords (underwater pluggable cords) and how are they used?

Halcyon E/O cords are versatile, underwater pluggable connectors and are standard equipment on the Apollo line of underwater film and video lighting; they are also available as an upgrade on all Explorer lighting systems. Slender two-pin connectors allow the user to disconnect the camera, housing, and light heads from our waist-mounted, high-capacity NiMH battery pack. This often-overlooked feature is highly prized by underwater filmmakers returning to the stern ladder in heavy seas, clamoring up the steep sides of a sinkhole, or seeking to switch between video and conventional light heads. E/O cords also allow divers to carry a back-up light head and switch while underwater.

Divers often ask how the term E/O was derived. E/O was the name used for these fittings when they were first manufactured by Electro-Oceanic, Inc. Over the years, through mergers and buy-outs, Electro-Oceanic has disappeared from the business landscape. Now in the fourth generation of the design, the term E/O is still associated with this connector, but we now refer to them as underwater pluggable cords.