If you're installing a window AC into a horizontal sliding window, you may wonder how to tackle the opening above. As you'll see, there's a simple workaround.

Most in-window air conditioners are meant to fit inside vertically-sliding windows only, meaning those with larger, horizontally-sliding windows in their house are left out.

Over the last seven years, I've tested 34 of the best air conditioners, and the Midea Duo Smart Inverter Portable Air Conditioner tops all of the portable units on my list.