Brass 45* flare fittings are a brass fitting with a 45* flared end which creates a sealed connection usually used with brass and copper tubing. Long flare nuts are a longer length than standard flare nuts and are used to tighten the tubing to the mating fitting. These fittings can be used with air, cutting oil, diesel fuel, fuel oil, mineral oil, refrigerant and water. They are highly corrosion resistant and can withstand up to 2,800 PSI.