It's the 50DN, used on big buses, gear driven. Most are 24 volt, but I think it can be had in 12 volt, 24 would be much better. The 5oDN is oil cooled and pressure lubricated with a line from the engine and a return. It's pretty big, looks about like a trash can
. These are the end all do all of alternators, everything else are just posers compared to it. They are designed to run at max 270 amp load for at least 1,000,000 miles. Two of them and a pair of 5000 watt inverters should be able to run my boats 120 electrical load while cruising. Including the air conditioning. I like the Victron inverters for the "assist" feature, which would be nice when we only have a 30 amp service available or low voltage situations. However, I am VERY impressed with the folks at Magnum Energy. Great products and excellent service. When you call there you will actually talk to an American tech, that knows his product.