Yep, that's all it says. What is a "chassis"? Well, it may be "a car's steel framework." Or it may be "the reflecting enclosure housing the ballast and lampholders in a fluorescent luminaire." Perhaps "the metal box that encloses amplifier parts"?
You may also be curious about how much power is provided by a "$300 watt" supply.
But now you're just being greedy.
It's free, you don't need to know what it is. Come and get it.