The present invention relates to a device (1) for mixing of a liquid and a powdered substance in a bottle. The device comprises a body (2) including a grid (3) having a plurality of openings (4) and a rim (6) surrounding the grid. The device comprises at least two elongated apertures (8) arranged in different radial directions in relation to a central part (9) of the body, to allow a part of the liquid to pass through the device without passing through the openings of the grid, and each of the apertures has a cross-sectional area which is more than twice as large as the cross-sectional area of the openings of the grid.
