Simplex is a high technology company that designs and manufactures electrical test systems (load banks) and fuel supply systems for the standby power generation industry. Their products are used in mission critical environments by companies like Cummins, Caterpillar, General Electric, and various branches of the United States military. Simplex equipment is also relied upon by hospitals, schools, public utilities, and in the servicing of jetliners, the Space Shuttle, destroyers, cruisers, nuclear submarines, and locomotives. The company emphasizes creative design and product development, tailored to meet customers' exact requirements. Simplex has been in business since 1934, with headquarters in Springfield, Illinois, and employs over one hundred and fifty people.