A freely connectable chest unit assembled from two sidewall panels, a top and a bottom panel, a back panel, and a door. A first fastening mechanism firmly connects the top and the bottom panel to the sidewall and the back panels, and enables vertical connection of two or more chest units. A second fastening mechanism enables horizontal connection of two chest units at their adjacent sidewall panels. The door may be connected at one side to one of the two sidewall panels by means of a door-closing mechanism so as to be automatically or manually closed. The door is provided with a size-adjustable lock-installing opening to enable installation of differently sized locks on the door. The lock includes a projection enabling the door to be freely openably closed to the chest unit, and a locking hook enabling the door to lock and open only with a key.