Abstract: A container assembly including a container tray and a container lid mateable with the container tray. The container tray includes a base flange, a tray panel, and a surrounding tray sidewall extending therebetween. The tray panel includes a recessed storage region in which various items (e.g., medicine) can be stored or contained. A plurality of protrusions extend from the tray sidewall. Each protrusion can include upper and lower tapered surfaces. At least a portion of the upper surface is substantially flush with the tray panel. The container lid includes a lid panel and a surrounding lid sidewall extending from the lid panel. A plurality of recesses are formed into an interior surface of the lid sidewall. Each recess is configured and positioned to securely engage a corresponding one of the plurality of protrusions when the container lid is mated to the container tray.