These fittings are typically used for a fuel regulator, however they may be used in any application where an adapter and an O-Ring is required. Our fittings provide superior strength with easy and fast assembly. High quality Viton o-rings provide a consistent and leak-free seal, even when used with racing fuels and oils. And finally, our black anodizing adds a final touch of stealth and quality that our customers expect from Treadstone Performance.