Abstract: Containers having a cover and a base provide covers that may be locked together. In addition the container covers may be locked to a sidewall of the container base. The container cover includes a first closure portion and a cover engagement portion. The base includes a second closure portion and a base engagement portion. The first closure portion of the cover is sealingly engageable with the second closure portion of the base to define a sealed storage area. The cover engagement portion of a cover is releaseably lockable with the cover engagement portion of a second cover to form a locked cover stack. The cover engagement portion of the cover is also releaseably lockable with the base engagement portion of the base.

Abstract: The container can be locked into a stack of containers. A container cover locks onto the top of a container base to define a sealed area for storage. Additionally, the bottom of a second container base can be locked onto the top of the cover of a first container. In this fashion, when closed containers are stacked, they form a locked stack that is more structurally rigid and therefore less precarious than a traditional, non-locked container stack. When not in use, the bases can be formed into a nested stack, and their covers can be locked together to form a locked cover stack. The locked cover stack can be locked to either the top or bottom of the nested base stack to form a rigid stack. In some embodiments, a cover can be turned upside down and its bottom face locked onto the bottom face of a base.