ITEM NAME:2x 8MM Non-Return One Way 5/16 inch Air Fuel Oil Check Valve crude oil engi I2I6 2x 8MM Non-Return One Way 5/16 inch Air Fuel Oil Check Valve crude oil engi I2I6 This valve prevents fuel from returning back to the tank and keeps it in the fuel line, so if you have a vehicle that is hard or slow to start because the fuel is returning back through the lines this will solve all your problems. Not only is it suitable for Fuel injection, but also for water, petrol, crude oil engine, oils, and other fluids. The life of Aluminum head is longer than plastic head Arrow marked on valve, showing fluid flow direction, Prevents fuel from returning back to the tank and keeps it in the line. Also great for water pressure pumps & galley pumps which are not self-priming Professional grade non-return valve - for marine, automotive, caravans/RV, and agriculture. Fit for Carburetors and low pressure fuel systems Easy installation and replacement