stainless steel, dark patina, leather.
This is a solid metal version of the device seen in the film that Poe gives to BB-8. It's a storage device containing a map to Luke Skywalker. It has all the details seen on screen from the Blu-ray. They were modeled in there meticulously, going through frame by frame. It doesn't look like the one in the Visual Dictionary because the VD one is shown wrong. My piece matches the on screen movie prop.