normally select the second electric circuit when not operated and preferably must be operated to select the first electric circuit therefore preferably the device is adapted such that the plunger automatically returns toward the backward position when the selector switch is released in an embodiment shown in fig1 the second switch 8 is arranged in a device 300 so that the backward position of the plunger is dragged in a predetermined distance behind the forward movement of the plunger therefore when a forward movement of the plunger is stopped the plunger may from its current position automatically retract over a predetermined relative distance rather than to an absolute position in other words the plunger does not always automatically return to the back end position but may retract only over a predetermined distance relative to a starting position from which the plunger is retracted thereby the components of the dental material may be dispensed and as the dispensation is stopped the plungers may retract a little to release the components from pressure exerted for dispensing thus afterflow of the components upon stopping dispensation of material may be prevented the device 300 further comprises the first switch 7 which is activated when the plunger reaches the front end position the plunger 301 of fig1 is shown in greater detail in fig1 a and 11 b the plunger 301 has.