Originally Posted by David Gladwin

..............And why not ? Festo fittings are just absolutely fine as SO many fine engine and tank accessory manufacturers prove !

And there's nothing at all wrong with Tygon either, been using it on board for years. Of course it's size is not compatible with Festo fittings , it was never intended to be. Some of my tanks have had Tygon inside and out for over 13 years, still fine !!