It's an inner and outer frame that fit inside each other. The outer frame is held to the jeep with two bolts, and the zipper. The inner frame is attached to the tailgate with four bolts and the window is held to each with about five million 1/4x20 bolts and retainer strips. The back window and frame can still be removed when you want to drive with the windows out, but the top can't be folded down with the outer frame still zipped in. That's not a big deal to me because I usually take the side windows out to get the airflow and leave the top up for shade anyways. I did score another back window on Craigslist so that I could use it like normal if I want to, I doubt it will see much use though. It's amazing how nice it is to open the tire carrier, tailgate and back window with nothing more than a pull of the stock tailgate handle!