3/4" In and Out tank closure 890S or D7171.
Fits standard tank openings, and has 13/16" distributor oring.

Commonly used on whole house carbon tanks and acid neutralizing tanks.

For new installations, we recommend using the new 1" heads, as they allow for easy connection with the newer "twist and lock" top distributors, and the 1" head uses the larger 1.05" O.D. distributor pipe ( commonly made with 3/4" PVC pipe ).