Parker A-Lok 12-8 LTN 3/4" Tube 1/2" NPT Male Connector, double ferrule, 316 SS.  Like the Parker CPI 12-8 FBZ-SS 316 Stainless Steel Compression Tube Fitting, Adapter, 3/4" Tube OD x 1/2" NPT Male but with an added ferrule rine at the compression end.