Flare to AN Straight Cut Thread; Size: -4AN Flare x 3/4-16in.; w/O-Ring Adapter Fitting; 6061 Aluminum; Anodized Black;. Flare to AN Straight Cut Thread. Fitting Size: -4AN Flare x 3/4-16in. Vibrant Performance oil system products are designed and manufactured to the utmost standard in quality and reliability and have earned the trust of industry professionals throughout the world.