A device (1) which includes a dispersing and/or homogenizing tool (2) and a pump (7) located on the same shaft (10), wherein a pumpable material can be fed from a receptacle, especially a container (3) or a pipe, to the dispersing and/or homogenizing tool (2). This material can be mixed in the dispersing and homogenizing tool (2) with an additive, which is led through a feeding line (5) and a region (5a) arranged concentric to the supply line (4) to an opening (6) before the dispersing and homogenizing tool (2). The pump (7) arranged at a distance before the opening (6) and before the dispersing and homogenizing tool (2), and has a pumping pressure in the flow direction, which, in the region of this opening (6), is less than the suctioning pressure of the tool (2). For influencing the pressure in the supply line (4), a device for changing or reducing the size of the cross section of the supply line (4) can be provided, which is preferably formed as a blocking device (8) in order to be able to also completely close the supply line (4).