Works with the following Dogtra Dog Training Collars: 175NCP (Serial Number less than 103471), 200NCP (Serial Number less than 111361), 202NCP (Serial Number less than 101961)/plus 3-3 splitter, 1800NC (Serial Number less than 100121), 1802NC (Serial Number less than 100101)/plus 3-3 splitter, 1803NC (Serial Number less than 100101)/plus a 3-3 splitter, and 1804NC (Serial Number less than 100126)/plus (2) 3-3 splitters. Black 5mm female and two yellow 3mm male connectors.