Several acceptable manufacturers may be listed in the specification and a level of quality also may be specified. The contractor, subcontractor, or supplier may have a preference for one of these products, based on price, availability, quality, workability, or service.
A list of acceptable manufacturers can be included in the specifications, along with a standard of quality that is also defined. The contractor, subcontractor, or supplier may prefer one product over others due to factors such as price, availability, performance, and maintenance requirements.