Abstract: Heavy duty spools having the capacity to hold at least about 375 to 675 pounds of product, such as between about 2,800 and about 3,000 unfilled plastic or paper bags which are sized to hold disposable diapers, are disclosed. The heavy duty spools of the instant invention are preferably fabricated from paperboard materials and include two flange plates connected by a hollow outer core. The hollow outer core is formed from a plurality of corrugated interlocks, each having locking arms on the ends thereof. The flange plates have central openings and a plurality of anchoring slots spaced around the central openings. The anchoring slots extend radially from and intersect the central openings and cooperate with the locking arms of the hollow outer core to anchor the hollow outer core snugly against the flange plates. Interlocks, when assembled into the hollow outer core, form unique ribs which lend support to the hollow outer core.