This is the Arri HMI M40/25 Set 4kW, the strong version of the M40 equipped with a 4KW lamp. You need a 32AH power on set to run it in this wattage. The Arri M series combines optimized weight and lightoutput with smaller size and more felxibility. You can use two different lamps inside one fixture. This gives you more variety of lightoutput on set. The M40 in this 4kw version needs a 32AH blue plugg to run, but the same lamphead with 2,5W lamp built in, can be run from any household plugg. This makes it an ideal Lamp when changing of location might occour and your not sure which power you will have there. Just order an optional set of 2,5 Burners with this set.