Some fire engines have a fixed deluge gun, also known as a master stream, which directs a heavy stream of water to wherever the operator points it. An additional feature of engines are their preconnected hose lines, commonly referred to as "preconnects". The preconnects are attached to the engine's onboard water supply and allow firefighters to quickly mount an aggressive attack on the fire as soon as they arrive on scene. When the onboard water supply runs out, the engine is connected to more permanent sources such as fire hydrants or water tenders and can also use natural sources such as rivers or reservoirs by drafting water.