In a carrier packer, a centering device has two series of flexible tabs (23, 24), aligned along two parallel shafts (25, 26). The shafts rotate the flaps in two alternative angular positions. In a lowered angular position, the tabs are introduced partly in the cells (16, 17) of a carrier (12), to guide bottles towards the center of the cells. In an angularly raised position, the tabs are rotated away so as not to interfere with the bottle necks once the bottles have been fitted in the cells, so that a conveyor may take the carrier away.