Bulker box

A bulker box is a 20-foot dry-bulk container fitted with three or four round loading hatches in the roof and discharge openings in the door end, used for free-flowing dry commodities: malt, coffee beans, grain, resin pellets, and fertilizer. It is not an open-top: the roof is closed steel, and the hatches let the box be filled from above by gravity or pneumatic line and then tipped or gravity-discharged through the door-end ports. The frame and corner castings follow ISO 668 and ISO 1496-1 so it handles as a standard 20-foot box. The seed wording calling it a converted open-top is wrong; it is a purpose-built closed bulk container.