I REALLY hated not having a screen door. This door has a small screen in it, but if you open the windows, you obviously have to have the entire door shut at all times. I found it to be far more of a bother than most doors that come with a separate screen door and the opportunity to leave the door latched open/secured to the trailer while in use.
We COULD have made a wooden screen door that would have worked. However, since it appears that most older motor homes (what we got our screen door off of) and older trailers have a pretty standard size screen door, it fit perfectly.
Due to the way the original door is installed, the screen door must be installed to open IN instead of out. It folds back towards the inside cupboard/sink area open. When not using it, we open the sliding door on the screen door, grab the doorhandle and shut the door.
It works wonderful and is one of my favorite additions to the trailer.