A preliminary type, form, or instance of a system or system element that serves as a model for what comes later. Risk reduction prototypes are used to materially reduce engineering and manufacturing development risk at an acceptable cost. They can be at the system level or can focus on sub-systems or components. Prototypes can be used to reduce technical risk, validate designs, validate cost estimates, evaluate manufacturing processes, and/or refine requirements. Competitive prototypes are produced by two or more teams who are competing for a contract award.