There are two general types of baffles: plastic pipe
(sanitary tees) and built-in wall baffles. Baffles
should be at the inlet and the outlet of a septic tank.
Baffles slow the sewage flow rate, promote proper settling,
and prevent scum from entering the absorption field.

The outlet baffle may have an "effluent filter" which will trap
any solids or garbage (i.e., tampons, etc.) from going to the
leach lines. This filter will need periodic cleaning.