This movement tray is composed of 2 layers of 3mm MDF. The tray holds 5, 20mm round bases. The spacing allows for models that overhang their bases and is designed so that multiple trays can be used to for either a line or other shapes that represents a horde. The spaces are slightly larger than 20mm to allow for extra paint or material that may be on the base. We use high quality MDF which does not warp when primed, painted and decorated to match your base design. The kit comes with 5 magnets and holes have been cut into the base for easy assembly. The tray comes unassembled and requires either wood or super glue to assemble.