The disclosed technology provides a device for sealing an aperture in a tissue of a body lumen. The device comprises a flexible support member having a base having (i) a central portion and (ii) one or more lateral support portions, to engage and/or hold a sealable member of the device against an interior surface of the tissue when the device is in the sealing position. The lateral support portions provide additional support surfaces to engage peripheral portions of the sealable member against the interior surface of the tissue.