The F81200057 is a Flight Step Electrical/Environmental System (EES) made by Rolls-Royce. It is used as a cost-effective, lightweight way of providing cooling, heating and pressurization to the engine's environment in both military and commercial aircraft applications. The system is also highly flexible and can be adapted to a range of engines and components. It is compatible with a variety of equipment and supports both long-term and short-term usage.