In one embodiment a hanger has two interlocking regions, each located at the lower corners of the hanger arms. The interlocking regions have a hole that extends at least part way through the body of the hanger and an extruded lip that extends beyond the body of the hanger at the interlocking region. In one embodiment the outer surface of the interlocking region is narrower than the upper hanging arms of the hanger and the outer edge of the extruded lip is substantially co-planar with the outer surface of the upper hanging arms. This allows the upper hanging arms to be in direct contact with each other when the two hangers are locked together, creating a smooth upper surface.