A manual device extends in an axial direction and includes a housing having a first housing portion and a second housing portion. First and second heads are each axially movable between a use position and a stowed position. The first head is in the stowed position when the second head is in the use position, whereas the second head is in the stowed position when the first head is in the use position. The first head and the second head both are carried by a single carriage movable in the axial direction and arranged inside a barrel. A groove forming a cam track is formed by a first shoulder of the first housing portion and by a second shoulder of the barrel. A lug of the carriage cooperates with the groove.