When I moved into my apartment I found it had a through-the-wall air conditioner sleeve. I ignored it and installed my window air conditioner. When that old AC died about 3 years ago, I was told by the co-op board that the rules had changed and I had to use the sleeve. I guess I should pay more attention to coop board announcements. My problem was that next to the sleeve was a 110V outlet but every AC that fit the sleeve required 220V.
After being quoted over $1000 to run 220V to the sleeve I was desperate to find another solution. Luckily, I found the Quick 220 Power Converter. All it took was the 110V outlet near the sleeve and an extension cord from another 110V outlet on a different circuit. Instantly, I had two 220V outlets. And at $160.00 I was very happy with the price. They also throw in an outlet tester because both 110V outlets must be wired correctly (not something you can assume in an old apartment) for the Quick 220 to work.