Excelvan 2 Packs 6MM/0.24Inch 1/4&rdquo; Chrome Aluminium Fuel Non-return One Way Check Valve Oil Petrol Diesel Marine Water WARRANTY: 1 year with 100% satisfaction and zero hassle returns guaranteed. FIT FOR: Carburetors and low pressure fuel systems. The life of aluminum head is longer than plastic head. FUNCTION: Arrow marked on valve, showing fluid flow direction, prevent fuel from returning back to the tank and keeps it in the line. NON-RETURN: Valve, professional grade, ideal for marine, automotive, caravans/RV and agriculture. APPLICATION: Great for water pressure pumps and galley pumps which are not self-priming.