Some Mitsubishi and possibly other makes or model's USB ports do not output enough power for wirless usb adapters, particularly our Picasou models. If you're finding your ottocast shuts down, or wont start up, this cable may be required as well as a phone charger with an output of 2.1amps or higer to give the ottocast enough power to function. We have found it's a mixed bag, as to whether you need it or not, so if you're having power supply issues, you may need to purchase this cable, and a suitable car charger.