This is the older, smaller AquaValve that uses 6mm (external) tubing, NOT the blue 9mm line. Autopot's increased the tubing diameter to help prevent blockages and problems, but we've found some old stock and are ready to pass them on cheap to anyone who still uses the older fittings or wants a very cheap valve system! These are mountable in all trays, however newer models based on the 9mm tubing + grommet feed hole will require sourcing of appropriate sized replacements.