​Superlok i-Fittings and valves have a revolutionary, leak-free design that takes the guesswork out of installing tube-end fittings and valves.  Installers have experienced far too many leaks due to improper tightening procedures.  Over-tightening and under-tightening the compression nut is the biggest cause of failures.  To eliminate this problem, Superlok has a built-in gap gauge installed on every fitting. Now, an installer can simply tighten a fitting until the patented, built-in gap gauge pops off... for a perfect connection every time!