A cage includes an inner male component, which is annular, and an outer female component, which is also annular, the upper surface of the inner component and the lower surface of the outer component forming outer surfaces that define the height of the cage, the inner component engaging in the outer component and being able to slide in relation to the outer component and having a blocking device for blocking a longitudinal displacement of the inner component in relation to the outer component, the cage being provided with a device which adjusts the height and acts individually on one end and the other end of the longitudinal axis of the inner component, a short side of the inner component and a corresponding short side of the outer component each being provided with a slot for the insertion of an adjustment tool.
