The 25064A000 Drain plug is a standard 1/4" MPT plug.
The 1/4" MPT threads actually measure about 7/16" in diameter.

The plug is sold without the o-ring, but the o-ring is available seperately.
See Key #21 for the o-ring.

This drain plug is used in 2 different places; there is one on the side near the bottom of the diffuser
housing and one on the strainer housing.