Round the sides
Many case-makers offer variants with and without side windows but opting for a window can cost you dear. If you go for the cheaper option but later decide to go for a windowed panel, you may be able to buy one as an after-thought. However, you'll have to pay even more for it and end up with a plain panel that you probably won't need again.
There's a dual-locking system for the side panel and the same key is used for both locks - which you may or may not think is a good thing.
What might be a problem, though, is the fact that the dual-lock arrangement means that you can't reverse the front door to hinge on the left, rather than the right.
Left and right side panels are secured with three thumbscrews a piece and the left panel has a handle to help slide it off.