Abstract: A system (10) for attaching a cover (12) to a container (11) and for closing an opening (21) in the cover (12) with a plug (13) utilizes a container (11) having an upper lip (16). The cover (12) is made of an elastomeric material and has handles (30) each having a notch (31) therein to receive the lip (16) of the container (11). A ridge (32) depends from the periphery of the opening (21) in the cover (12). The ridge (32) is generally square having sides (33) and corners (34). The ridge (33) includes a notch (35) formed in each side (33), and ribs (36) are positioned at each side of the notches (35). The plug (13) has a generally cylindrical stem (41) whose diameter approximates the length of a side (33) of the ridge (32). Diametrically opposed tabs (45) are positioned on the stem (41). By aligning the tabs (45) with the corners (34) of the ridge (32), the stem (41) can pass through the opening (21). Then rotating the plug (13) allows the tabs (45) to pass over the ribs (36) and into opposed notches (35).