Doors can be made to open as one large door the width of the rack or in two doors on a double rail,  so 50% can be opened at any one time.  

For example: the video shows a two door option.

In this video Eurostar needed a simple solution for inventory control for its nuts and bolts.

The secure racking increased better stock control and usage audits for an outside components supplier.

Sliding doors can also be mounted on partitioning to sub-divide areas. Depending on the application, the doors can be top rail hung or bottom run on wheels. 

Doors can be solid or mesh, single or double, even on telescopic rails which have no permanent bar to block aisles, allowing access for taller items such as moveabe safety steps and forklifts.