US Patent 6923338 Food container with interchangeable lid—base seal design

There is provided a container having both male and female sealing regions disposed about its periphery in a pattern making it possible to seal a container with another container having substantially identical sealing regions. The male sealing regions used in the practice of the present invention may take the form of a U-shaped ridge which is undercut along at least one leg of the U. Typically, a container will he thermoformed from lightweight thermoplastic material giving the U-shaped ridge considerable flexibility. The female sealing regions used in the practice of the invention may take the form of an undercut channel adapted to receive and match the undercut U-shaped ridges found in the male portion of the container wherein the walls and base of the channel are sufficiently flexible that the undercut portions of the U-shaped ridge are urged into engagement with the undercut portions of the channel and the crest of the ridge is urged into the channel.