Referred to as a cake drum, this is the strongest type of cake board. It has a bonded fibre board inner which is covered on the top and sides with a fern textured, silver coloured foil and with white paper on the base. The finished cake drum is approx 0.5'' (12 - 13mm) thick. 
These cake drums are supplied shrink wrapped in 5s, but you can buy a single unwrapped drum.