@Rich-O-Brien yeah. I also wonder how long they will last. Actually we're replacing all the windows in our house this year so this one doesn't need to last a real long time. A neighbor down the street has the same kind of windows and has a number of broken ones so I'll print some for him, too.
I have no idea but my guess is they were used on another type of window, too.. And maybe in a different way that would make the the curves, notch, and second set of holes required. Those features certainly aren't used in the application on our windows.
I like the new version better, too.
Thanks.