Note before downloading:
1: This is for MAME only and is not compatible with RetroArch.
2: If you've previously downloaded and set up the "MAME Atari 5200 Software System Custom Artwork File" (the one that uses the Themed bezels), then there's really no need to download this.
You just need to add the SA bezels to your existing a5200.zip overwriting the Themed ones; the bezel names are the same. Your original custom parameters are valid.
If you decide to download then read on.
This custom version of the Atari 5200 Software System artwork file, a5200.zip contains a multi-view lay file configured to work with the "bezelprojectSA-Atari5200" bezels pack. Any game associated with the pack can be set to display it's own bezel at launch. Games for which there are no "bezelprojectSA-Atari5200" bezels and therefore use Default Command-Line Parameters will open with the generic Atari-5200.png bezel.
The bezel png images are not included, so you will need to download the pack and drop the bezels into the artwork a5200.zip yourself.
You will also need to set LaunchBox Custom Command-line Parameters to allow MAME to choose the correct bezel for each game. This is explained in the download.
With MAME, your Atari 5200 game names and their bezel image names do not have to match.
Once downloaded, unzip the file MAME_Atari5200_SA.zip and read the enclosed text files.