A cabinet includes a top wall, a bottom wall, two opposite sidewalls, and a sliding door. One of the sidewalls defines an opening. A rail perpendicular to the sidewalls protrudes from an inner surface of each of the top and bottom walls, extends to the opening. The sliding door defines a slide slot in each of a top and a bottom. The sliding door is capable of sliding into the cabinet through the opening, with the two slide slots fitted around the corresponding rails.