This is a Bernette serger made by Bernina, about 25 yrs. old. We have several of these where I work. It might be a three thread or four thread, can't tell by looking at the picture. They aren't too hard to thread, there should be a diagram inside the door on the lower right. Pull the handle to the right and slide the door open and then pull towards yourself and the area where the threads go will be visible. They are workhorses.