A teat unit has a teat (4), a securing device (2, 3) for securing the teat (4) on a liquid container (1), and an air valve (23, 310), the securing device having a first securing part (2) and a second securing part (3) . The air valve (23, 310) has a first valve part (23), which is arranged in the first securing part (2), and a second valve part (310), which is arranged in the first or in the second securing part (3). The air valve (23, 310) opens and closes with respect to the second securing part (3) . The valve is preferably a diaphragm valve, and the first valve part is a valve diaphragm. This teat unit functions very reliably even at very small pressure differences between the bottle and the environment. Moreover, the range of function of the various teat units of the same type is relatively narrow, such that different teat units function very similarly and the air valves are actuated at similar pressure differences. (Fig. 4)
