The invention relates to a jet regulator (3) having a jet regulator housing (4), which has, on the housing outer circumference thereof, an external thread (5), by means of which the jet regulator (3) can be mounted in an internal thread provided in the water outlet of a sanitary outlet fitting, wherein an outflow-side housing end face (6) of the jet regulator housing (4) is designed as a grid or mesh structure, which has throughflow holes (7) for the water flowing through the jet regulator (3) and which has at least one tool engagement surface designed as a slit-shaped recess (8, 9) in this grid or mesh structure and intended for a turning tool. It is characteristic of the jet regulator according to the invention that a second slit-shaped recess (9) is provided in the slit base of this first recess (8), the second recess likewise being intended as a tool engagement surface, and that the second recess (9) has a smaller recess cross section than the first recess (8).