The Philips Avent Electric Breast Pump works with pumping bras, which have larger, slit openings through which you can fit the funnel of the pump body.
We suggest that you do not use a pumping bra with circular holes in place of slits. The way our breast pump is assembled, it is not possible to attach the pump body through the bra, therefore you need to use a bra with which you can fit the funnel through the opening.