This is a modular storage system.
When opened, the dwarer conveniently drops to 30 deg angle and exposes the content.
There are 9 combinations available (width x height): 1x1, 1x1.5, 1x2, 1.5x1, 1.5x1.5, 1.5x2, 2x1, 2x1.5, 2x2 (let me know, if you are interested in more sizes). Each module is 42mm. The depth of the housing is 2 modules.

Housing name starts with module type and ends with rail direction (N - top; S- bottom; E- right; W- left).

Drawer has a module type in the name. Mount rail also identifies module type.

Mounting plate is also provided in increments of 1, 1.5, 2 modules, to allow interfacing with support surfaces.

Backplate mounting is also available.
Backplate adapter can be attached to the module and slide on a backplate.
Backplate is available for skadis system.

Enjoy :)