An enclosure comprises a chassis, a front panel installed on the chassis, and a cover. The front panel defines an opening. Two mounting board are located on the front panel. Each of the two mounting board defines a first slots. The cover comprises a base wall and two sidewalls located on opposite sides of the base wall. A first latching portion is located on the sidewall. The first latching portion is slidabaly engaged in the first slot. The cover is slidable relative to the front panel to the base wall covering the opening or uncovering the opening.