What are those filled in areas on my Surface Laptop 2?

[Myvryn]

On my Surface Laptop 2, on both sides, there is a section of the chassis that looks like it was a filled in hole. they are located on the side just forward of the headphone jack (left side) and the multi-use connector on the right.

My first thought was that these were magnets for you pen, but that turned out to be not the case.

Anyone have any idea what these are?