The carburetor, despite all it advances: air bleeds, correction jets, acceleration pumps, emulsion tubes, choke mechanisms, etc., is still a compromise. The limitations of carburetor design is helping to push the industry toward fuel injection. Direct fuel injection means that the fuel is sprayed directly into the combustion chamber. The fuel injected nozzle is located in the combustion chamber. Throttle Body injection systems locate the injector(s) within the air intake cavity, or "throttle body". Multi-point systems use one injector per cylinder, and usually locate the injectors at the mouth of the intake port. The fuel injector is an electromechanical device that sprays and atomizes the fuel. The fuel injector is nothing more than a solenoid through which gasoline is metered. When electric current is applied to the injector coil, a magnetic field is created, which causes the armature to move upward. This action pulls a spring-loaded ball or "pintle valve" off its seat. Then, fuel under pressure can flow out of the injector nozzle. The shape of the pintle valve causes the fuel to be sprayed in a cone-shaped pattern. When the injector is de-energized, the spring pushes the ball onto its seat, stopping the flow of fuel.