AMAZING QUALITY SMALL AIR MAZE FUEL FILTER. I BOUGHT SEVERAL OF THESE FROM EARL FOUTS IN HIS SURPLUS STORE IN LAWNDALE SOMETIME IN TH 80`S. NOT GOING TO USE THEM ALL SO LUCKY YOU. THE QUALITY IS SUPERB, FEMALE MOUNT THREADS AT TOP ARE 1/4 UNF AND FEMALE PORTS ARE DASH 6, 9/16 X 18. THE FILTER IS VERY FINE AND GRAVITY FEED IS NOT ENOUGH TO GET FUEL THROUGH QUICK ENOUGH THEY NEED TO BE HAVING FUEL PUMPED THROUGH THEM. THEY STRIP DOWN EASILY SO AS TO CLEAN, NEVER NEEDING NEW FILTER INSERTS OR WHATEVER AND UNLIKE PLASTIC FILTERS ARE NOT A FIRE RISK.