With these constraints in mind, the US Navy developed what was initially known as the CVN-21 program, which evolved into CVN-78, "Gerald R. Ford". Improvements were made through developing technologies and more efficient design. Major design changes include a larger flight deck, improvements in weapons and material handling, a new propulsion plant design that requires fewer people to operate and maintain, and a new, smaller island that has been pushed aft. Technological advances in electromagnetics have led to the development of an Electromagnetic Aircraft Launch System (EMALS) and an Advanced Arresting Gear (AAG). An integrated warfare system, the Ship Self-Defense System (SSDS), has been developed to allow the ship to more easily take on new missions. The new Dual Band Radar (DBR) combines S-band and X-band radar.