Retail display header and associated assemblies

A retail display system comprising:

• a retail display fixture including:
• one of a shelf and a rod for supporting items offered for retail sale, and
• a cross bar extending substantially horizontally in orientation;
• and
• a header box comprising:
• a front panel having a bottommost edge,
• a rear panel initially formed coplanarly with the front panel and folded about a first fold line of the header box relative to the front panel to extend entirely spaced from and substantially parallel to the front panel, wherein the rear panel includes at least one depending flange extending downwardly from other portions of the rear panel, and
• a bottom panel initially formed coplanarly with each of the front panel and the rear panel and bordering the rear panel about a second fold line, the bottom panel being folded about the second fold line to extend between the rear panel and the front panel, and the bottom panel being positioned above the bottommost edge of the front panel and above the at least one depending flange of the rear panel;
• wherein a reception cavity is formed between the front panel and the at least one depending flange and below the bottom panel, and the header box receives the cross bar of the retail display structure such that the bottom panel contacts the cross bar so the header box fits atop the cross bar and the cross bar is contacted by and maintained between the front panel and the depending flange.