It's always a battle to get ACs designed for vertically opening windows to fit and work in sliding windows. I discovered the older model of this unit a couple years ago but held out on getting it. I finally gave in after I couldn't find anything else that works how I want and wish I'd just pick this one up when I first found it. Glad I got the newer model though as it's quiet and has some nice additional features. I noticed some local stores also carried it, but for a much higher cost than just ordering directly from Frigidaire. Will more than likely get another one in the future.