An apparatus for sealing a bag opening includes a retaining member and a slide member adapted to slide into said retaining member. The retaining member includes an elongated opening that extends through at least one open end of the retaining member. A bottom stop is provided at an end of the retaining member that is opposite to the open end of the retaining member. Alternatively, the retaining member includes an elongated opening that extends through both ends of the retaining member and the bottom stop is omitted. The slide member includes at least one protruding portion that protrudes from the retaining member when the slide member is slid into and retained by the retaining member. The slide member abuts the bottom stop of the retaining member when such bottom stop is provided within the retaining member. In cases in which the retaining member is provided with two open ends, the slide member may include two protruding portions that protrude from both open ends of the retaining member.