I bought this for my son's bunk bed. He's on the top bunk. It fit with an inch or 2 to spare (from top of the tent to the ceiling). I believe I needed 47" from the bottom of the mattress to the top of the tent. Most importantly, I needed a tent that opened on the ends so he could climb in. The opening on the side doesn't work for his bed since he's on the top bunk.There are 2 panels on each side and each end. They all unzip completely so basically 75% of the tent can unzip for ventilation and light. On the ends there are screened net windows. The sides do not have screened net windows.The mattress fits INSIDE the tent, not on top. That was the worst part -- trying to get a twin bunk bed mattress into a tent and THEN getting the mattress & tent up at the same time on the top bunk.There are 3 tent poles to insert to make the top taut. They aren't absolutely necessary because it will stay up without them due to the circular frame on the ends. You have to shimmy those poles into and through the tunnels on the top of the tent. I accidentally put the insertion point of those tunnels against the wall end and not on the open end by the stairs so inserting those poles took a lot longer than it should because I had to bend the poles at a 90 degree angle at each segment because the wall wouldn't allow me to do the entire pole all at once --- if that makes sense. So pay attention to the side where these 3 poles insert so you don't get the mattress up there with the tent on it and realize that you'd have to pick it back up and turn it 180 degrees... like I did.My 3 and 5 year olds play in there comfortably. I'm 5'5" and I can sit Indian style without having to crouch down. There's a pocket inside that you can put a cellphone, books/magazines, flashlight, a bottled water, etc. We put my son's tiny stuffed animals so they didn't get lost. I got the dark gray and it's pretty dark inside. Not a lot of light gets in through the fabric. It seems of great quality, but I've only had it a month. I stuck glow-in-the dark stars on the interior top of the tent and they stick well to it. I shine an extremely bright flashlight on them for about 10 minutes before my son goes to bed and it looks so awesome laying down in the tent looking up at the bright stars.I'd definitely recommend this tent for someone wanting it for a top bunk bed. If you're wondering if it will fit on the bottom bunk you will need to measure from the bottom of the mattress to the bottom of the top bunk. The tent is 47" tall so if it's less than 47" it's going to be too big for the bed.Photo #2: end fully zipped upPhoto #3: end fully zipped up, but with window screen exposedPhoto #4: same as #3, but showing how you can see through the tunnelPhoto #5: same as #4, but with flashPhoto #6: end completely unzipped showing other end completely zippedPhoto #7: side view with side opening completely openedPhoto #8: side view with side opening completely closedPhoto #9: interior view (w/ camera flash) of side panel with tent completely zipped upPhoto #10: same as #9, but showing table lamp light shining through tent fabricPhoto #11: interior view of closed opening with light on in room and door open (it's pretty dark!)Photo #12: interior view of light on in room and door openPhoto #13: stars stuck on tent ceiling I am a crazy cat lady, I have 5 cats and I love them a lot, but sometimes it's hard to sleep at nights with all of them jumping back and forth on my bed. So I bought this tent to hide from my crazy pets