A typical toolbox (at least in the U.S.) has a shallow tray with a handle (the "top layer") that sits above the deeper compartment of the toolbox. Small items (nails, screws, small screwdrivers, etc.) are stored in the top tray. If you need to get to one of the bigger tools (hammer, drill, etc.) you first lift out the top layer of your toolbox. You move the smallstuff out of the way in