OPTIBOX and AZBOX modules are inspectable stormwater retention and infiltration units. They allow the construction of underground storage basins with full visual and technical access inside the system. With integrated inspection channels, the blocks can be camera-inspected and water-jetted for easy maintenance and network monitoring. Lightweight, modular and extremely strong, OPTIBOX and AZBOX systems ensure three-dimensional water diffusion within the modules and can be installed beneath car parks, roads or logistics platforms without deformation risk.