Engineers and marketers work to develop the product concept. The problem that the product solves is described so that they can estimate market size, assess challenges and develop a successful marketing strategy. Engineering then develops a project strategy and engineering specifications, identifies major technical risks and design challenges, and estimates the product development price and schedule. The CONCEPT phase is completed upon Product Approval.

Engineering proceeds to develop a fully functional prototype according to the engineering specification developed in the CONCEPT phase and agreed upon at Product Approval. When satisfactory performance is demonstrated, DESIGN completion is achieved upon approval to proceed to the next phase.

Several units of the product are built (usually 3 to 5) using the parts and construction similar to that of manufacturing. (For example, circuit assembly is on etched circuit-boards instead of protoboard.) The units are tested against specification and refinements made. EVALUATION is completed upon approval for the next phase.

Refinements from EVALUATION are incorporated into a more extensive build of 5 to 10 units, which are subjected to environmental and field testing. VERIFICATION phase assures that the product is ready for manufacturing and that all documentation (electrical and mechanical drawings, parts list, specifications, assembly and test procedures) has been completed. The final product design is deliverable upon completion of this phase and the first manufacturing run is ready to commence.