The BG Fuel Systems Fuel Logs feature 100% aircraft-grade billet aluminum construction. These anodized fuel logs feature an adjustable design that allows the fuel log to be adjusted to fit 4150 and 4500 series style carbs. Triple O-ring sealed. High volume capacity with red anodized finish. Includes adjustable poppet bypass valve with spring and pills. For use with belt-driven fuel pumps using gasoline or alcohol. Additional bypass pills available separately.