This is a stencil for iOS designing. It allows you to frame your design work in the manner in which it will be framed in use. It also securely attaches to your notebook and doubles as a page marker.
The stl file labeled "iOS design template 50 scale" is a 1/2 scale to the iPhone 8 plus.
The stl file labeled "iOS design template full size" is a to scale stencil of the iPhone 8 plus.