The Switronix 20" Powertap Cable for C300 (XP-DV-C300/20) is an XP model cable -- XP models are known for their versatility. The cable's main use is to connect a PRO-X series battery to a Canon C300 Cinema Camera, and it can additionally be used with various accessories. It features a regulated DC connector for connection to the C300 (with an increased amperage allotment), and an unregulated P-Tap output for connection to accessories. Red and green LED lights indicate the status of battery power.
The cable can also be used with cameras other than the C300, but compatibility would first need to be confirmed (at least by phone with Switronix.)