Image is Representational - See Manufacturer Specs | Circular Connector - Cable Mount Plug - 40 Contacts - Solder Pin - Push-Pull - Copper Alloy Body. The 2101551-1 TE Connectivity Circular HD Connectors offer the ease of push/pull, self-locking mating for I/O applications. The connectors are widely used in military and civilian use, including radio equipment, medical equipment, test equipment, audio and video equipment, data acquisition and industrial control.