This Air Lift swivel elbow fitting is specified as 1/8-inch MNPT x 1/4-inch PTC in the catalog. The entry identifies the part as a swivel elbow fitting with the given thread and push-to-connect dimensions, suitable wherever a 1/8" MNPT to 1/4" PTC swiveling connection is required, and reiterates the same fitting description used in the source fields without extrapolating additional use cases.
Air Lift Swivel Elbow Fitting - 1/8in MNPT x 1/4in PTC