Description of this AC said 12,000 BTU but when I received it, on the box it said 6,500 BTU (2017 DOE test standard); 12,000 BTU (Ashrae 128 test standard).  I was unaware that there is more than one kind of BTU rating, and since I live in the U.S. I assumed the product would be described based on its rating by the U.S. Department of Energy.  I have kept the air conditioner because of the difficulty of returning it -- I don't drive, and the complexity and cost involved in returning a device of this size led to my decision to keep it. But I do believe the ad was misleading; no reference was made to a BTU rating of 6,500.