This is the main baseplate for the Chameleon 1 enclosure system. It has all the pre-center-punched divots as the original so you can easily locate your board's mounting hole placement.
This is a replacement or spare part for the Chameleon 1 enclosure system.
Reasons why you may need or want this part:
1) Since the Chameleon 1 screws are self-drilling, repeated loosening and tightening operations can cause the self-drilled holes to enlarge over time which can cause the enclosure to feel "loose". This is the best way to tighten things up again.
2) You're ready reuse your case for a different development board but don't want to purchase the entire enclosure again. Go from an Arduino case to an Olimex SAM7, for example. Just get a new baseplate and faceplate and you have a different enclosure for a different development board - that's the beauty of the Chameleon 1 enclosure system
2) Perhaps you mis-drilled your original baseplate
Don't forget to snag a fresh 1/8" drill bit (sold separately below) for a nice clean set of holes in your baseplate.