I used this to replace another skylight and it was one of the few available that would work with the existing curb. Installation was a breeze other than having to remake part of the light well due to a slight difference the old one and this new one. This is a manually opening model. One small negative is that it takes 35 cranks to fully open the Velux. The old one took 18. It seems this one does open a bit farther though, so it's a fair trade. My one and only complaint is that Velux does not offer this skylight, indeed any other the VCM models, with a manual shade of any sort. If you want a Velux shade (which was the reason I sought out Velux originally) you must buy an electric model with remote control that costs nearly as much or more than the actual skylight. To me, an electric shade, or for that matter an electrically opening skylight, is just one more thing to go wrong. My actual curb dimensions are 26" X 38" which are a bit larger than the stated size for this unit, but it fit with no difficulty. Otherwise, it is a great product which I'm hopeful will give many years of service.
Energy Efficient, Sturdy, Easy to Install, Functional, Fits in Various Rooms, Well Made, High Quality