In naval hardware, fit to receive or fitting "for but not with" describes a weapon or system which is called for in a design but not installed or is only partially installed during construction, with the installation completed later as needed. This is done to reduce the vessel's build cost by not purchasing the system at the time of construction, or as a method of future-proofing a design. The term is usually used in regard to ships but sometimes extends to military vehicles, aircraft and other hardware.