These are effective because the combine the visibility of a lighted face with the efficiency of a box. The large flat surface allows for effective, and dramatic graphics. The background can be lighted with the letters blocking light or have the background block and the letters pop.
They are much more affordable than channel letters. The message can be switched out quickly.
These are constructed from Aluminum Extrusions into cabinets. You see them used inside and outside.
Indoor examples normally carry a higher level of finish, can be painted and are generally smaller. They are generally mounted on walls
Outdoor examples normally rectangular, but can be many other shapes.
These are commonly seen for retail stores such as restaurants, churches, schools, strip malls, self storage facilities and industrial offices.
Mounting can be wall mount, saddle mount, wrap around, between two poles center pole mount and cantilever.
Zoning of pole signs (a common way of mounting these signs) can be a zoning issue in Oceanside, Carlsbad, San Marcos and Vista where monument signs are strongly favored.