BrassCraft® 3/8 in OD x 3/8 in OD Forged Swivel Nut Union Connector can be used with fuel oil, liquefied petroleum (LP) and natural gas lines. Designed for use with aluminum, copper, brass and welded steel tubing that can be flared. Forged rod construction uses extreme pressure to produce uniformly dense material with height impact strength and resistance to mechanical shock and vibration.