Abstract: A breast interface assembly for connecting a breast pump to a nipple of a breast, includes a connector and a reversible element which has two terminal portions of differing internal diameters. The breast interface assembly is configured to be assembled in a first state, in which a first terminal portion of the reversible element connects with the connector, and the breast interface assembly presents a breast contact surface defining a nipple aperture of a first diameter. The breast interface assembly is further configured to be assembled in a second state in which a second terminal portion of the reversible element connects with the connector and the breast interface assembly presents a breast contact surface defining a nipple aperture of a second diameter. In at least one of the first and second states, the reversible element provides at least part of the breast contact surface.