FIELD: medicine.SUBSTANCE: invention relates to medical equipment and is intended for application in an electric toothbrush. The replaceable toothbrush head assembly for an electric toothbrush, having a handle portion and an output shaft for toothbrush head driving comprises a constriction portion with a hollow portion at its proximal end, the bristle portion at the distal end of the constriction portion, and the connection assembly. The connection assembly is located in the hollow section of the restriction portion and has at least two separate different physical positions, including the first discrete position and the second discrete position. The connection assembly comprises an additional coupling element and a hollow ring member. The coupling element has a movable valve portion extending along the length portion of the outer surface on one side of the coupling element, the movable valve portion is coupled to the coupling element upper surface with a bent portion and has a flat top portion extending down to the inclined portion passing to the second flat portion, with a horizontal outward protrusion. The hollow ring member has an outer surface which is joined to the inner surface of the toothbrush head constriction portion, securing the communication unit on the inner part of the toothbrush head, at that, the ring member has an inwardly projecting member with an inclined portion on its length the projecting member is located on the inner surface portion of the ring member. When the connection assembly is in its first position, the inclined portion of the ring member adjoins the inclined portion of the coupling element movable valve portion, providing easy removal of the toothbrush head assembly from the output shaft or its installation, and when the connection assembly is in its second position, the inclined portion of the ring member presses the coupling element flat upper portion, moving the flat inner surface of the coupling element movable valve portion to a
