Stacking containers

Claim 1

A stackable container having an open upper end, an underside with projections thereon adapted to cooperate with an edge of the upper end of a similar container, at least the upper and lower ends of the container being polygonal in plan view and said projections on the underside comprising: (a) an essentially polygonal projection having the same number of sides as the polygonal lower end of the container, the sides of said projection being parallel to respective sides of the container and spaced inwardly therefrom; (b) a plurality of corner projections between respective bottom corners of the container and adjacent corners of said polygonal projection, said corner projections having drain holes formed therethrough with removable plugging means and (c) further projections at positions between the polygonal projection and the bottom edges of the container and spaced from said corner projections, said further projections being spaced from said polygonal projection by at least the thickness of the upper edges of the container and said further projections and said corner projections defining between them channels corresponding in shape to the corners of the upper edge of the container, whereby a plurality of such containers can be stacked one above the other in a horizontally staggered corner-to-corner or edge-to-edge formation with each upper container having at least one said drain hole opening into a lower one when its respective plugging means is removed.