Spigot is Always Male, Socket is Always Female
How to find 3” schedule 80 PVC?
This fitting sis schedule 40. Both sides would fit sch 40 or 80 pipe, as OD of 40 & 80 is the same. Spigot side has the OD of the corresponding pipe, thus needs coupler
Socket
Spigot
Same size as pipe, thus needs coupler, or belled end of pipe
Fitting philosophy: the rationale for this type of fitting is convenience of inserting one size in the female part, and compact transition to a larger size. This works well in terms of structural integrity, because otherwise one has a female-female coupler with structural integrity issues at the transition. This allows a structurally sound design, but it requires a coupler or bell on the spigot side. Ie, a good solution that shifts the problem downstream (extra fitting required).