Patent ID: 8083084

Claim:
A container comprising first and second container elements that each has an axis, a base wall, side walls, and a flange that extends radially away from said axis from upper ends of said side walls when said base wall is lowermost, said container being closeable by placing said second element in an upside-down configuration over said first element, wherein: said first element has a first section constructed with its flange having at least one upward projection with enlarged top, and with its flange having a second section constructed with its flange forming an upward-opening undercut groove; said second element lying in said upside-down configuration over said first element, with said flange of said second element having a second section forming a downwardly-opening undercut groove that receives said upward projection of said first section of said first element, and with the flange of said second element having a first section forming a downward projection with enlarged bottom that lies in said groove of said second section of said first element; said first and second elements are identical with their flanges being sheets wherein each projection on one face of the flange forms a groove in the opposite face of the flange, each projection and the corresponding groove extending in a zig-zag path along a length of one of said flanges.