These boxes were designed to hold 8 510 or Airo Pro vaporizer cartridges.
They are made from a solid piece of wood that has been laser cut to form a box joint.
There is also a loose piece inside by design that is not glued down. It's purpose is to prevent the bottom of the carts or batteries from sliding around.
I have also had a few batteries fit in the hole with the exception of larger ones like the AiroPro battery.
***Battery and Cartridges are NOT included***
Wood grain varies.