This is a case for raspberry pi4 B model. It is modular, the walls snaps togheter, the top and the base are screwed togheter with . The top has an allocation for an heatsink. I can't find the link of the heatsink anymore, i'm sorry, but is a passive heatsink like you see in the foto. For the screws, they are hexagon screw screw M4x25mm, a nut have to be placed in the location under the raspberry case.