A brassboard contains both the functionality and approximate physical configuration of the final operational product.
[1] While representative of the physical layout of the production-grade product, a brassboard will not necessarily incorporate all final details, nor represent the physical size and quality level of the final deliverable product.
Exact definition of a brassboard depends on the industry and has changed with time.
A 1992 guide book on proposal preparation defined a brassboard or a breadboard as "a laboratory or shop working model that may or may not look like the final product or system, but that will operate in the same way as the final system".
The definition of a breadboard was further narrowed to purely electronic systems, while a brassboard was treated as "a similar arrangement for hydraulic, pneumatic or mechanically interconnected components".