A rackable, collapsible, and stackable unit including corner posts being foldable inwardly and downwardly, side bars connecting a pair of opposite corner posts, upper end bars connecting a pair of adjacent corner posts, lower end bars connecting the pair of adjacent upright corner posts, a core holder located on the upper end bars for retaining one end of a core, a plurality of hinges, one connected at each joint between each corner post and the side bars, and hinged support braces pivotally and diagonally connected between one of the corner posts and one of the side bars to hold the corner posts in an upright position when the unit is opened and which, in combination with the hinges, makes it possible to fold the corner posts inwardly and downwardly so as to lie substantially flat against the side bars.