New plumbing Fitting for 1/4" (6mm) OD Tube Push-In X 1/8" MPT.  Push-in end accommodates either copper and thermoplastic tubing for fast leak-proof installation and quick removal with simple retraction of the blue ring, leaving both fitting and tubing undamaged.  The fitting body requires either a 12 mm or 1/2" wrench for installation unless an adjustable wrench can be used.  Free S&H to USA.  20% discount for multiple item purchase.