BEST BUY For electricity supply, this was a top performer. The maximum load of 75 Watts was reached easily, current loss was minimal and power draw at standby was low. One minor drawback is that the mains socket sits directly on top of the cigarette lighter plug. While this means there are no trailing wires, it could make the unit difficult to fit in some cars. Still, the positives far outweighed this minus point, making the Ring our Best Buy.