I'm lost. The two pics of the back look like two different instruments.
It looks to me like the red part is removable; possibly a soft pad? Note that in the photo of the red back, there are two screws that correspond to two screw holes in the other picture of the back.
As for the instrument... I have no idea what it is. It doesn't appeal to me, so I wouldn't buy it, but YMMV.
I find it odd that there is an upper access plate on the back. What's that for?