400V Grow Lamps are the next generation of HID lights and output around 10% more usable light than standard 240v grow lamps, that are currently in use.
They require a different ballast to power them - we currently sell the Maxibright Promax Gold 600W/400v ballast with other models expected to follow in the coming months.
You can dim these lamps in the same way as you would a normal 240v lamp, the main difference is just the enhanced PAR output. They cost a bit more than 240v lamps at the moment, as they become the norm in the grow lighting industry expect the prices to drop to about the same level.
***Please retain original packaging for your lamps to validate the 12 month warranty***