US Patent 7588387 Barriers with interlocking sides

A barrier includes a housing having a front wall and an opposing back wall each extending between opposing sidewalls. The housing also includes a floor and an interior surface bounding a chamber, the chamber communicating externally through an inlet opening. A first inset projects into the chamber from the front wall so as to form a recessed blind pocket on the front wall. A second inset projects into the chamber from the back wall so as to form a recessed blind pocket on the back wall. The first inset and the second inset are connected together within the chamber so that the chamber encircles the connection.