Arrow Indicator: The arrow marked on the valve, indicating the direction of fluid flow, prevents fuel from flowing back into the tank and keeps it in the line. Material: The valve is made of aluminum, high strength and hardness and durable in use. Easy to Install: Easy to install and replace. Ideal for marine, automobile, caravan/motorhome and agriculture. Application: Suitable for use with gasoline, water pipes, biodiesel, coolant, etc. Ideal for water pressure pumps and kitchen pumps that are not self-priming.