Eish, that's a bit steep, even for a tank that has two decks. I'm also confused about the tank capacity. In the blurb, it says "1 x UD Goblin Mini V3 4ml RDTA Tank". Then it implies that the extension tube, purchased separately, increases the capacity to 4ml. If it's a 2-3ml tank that increases to 4 with the extension, that seems like a whole lot of extension for not very much extra capacity.