Five o-rings used on the Fleck 5600 Injector Drain Module.
13303, 13302,12638, and 2 of 13301
If the Valve is over 5 years old, these orings may not re-seal properly if you take the Injector Drain Module off while working on the Valve.
That is why it is recommended to replace these when you work on this portion of the Valve.
And of course if you already have a drip in this area, you'll need to replace these orings.
NOTE: The most common leak on the Fleck 5600 usually comes from the Main Piston, so check that first when trouble shooting Leak problems.