The manufacturer refers to these tool organizers and as the Click and Go System because of the way they clip together. I still think of them as L-Boxxes.
That's because when the system came out it consisted of four different L-Boxxes, modular organizers that can be ganged together for easy storage and transport. It now includes wheeled carts and other accessories so I can see why they call it a system.
For more information on L-Boxxes see the video below or this comparative review of the Bosch, DeWalt, and Festool modular storage systems.