A modalmetric fibre sensor comprises a multimode sensor fibre, a light source for launching light into the multimode fibre to produce a multimode speckle pattern of light at an end of the fibre, a single mode fibre to receive light from the multimode speckle pattern and a detector connected to the single mode fibre to detect the received light from the multimode speckle pattern. Preferably, such a cosmetic or topical composition has sodium hydrogen phosphates andor sodium polyphosphates in an amount about 0. 1 to 10 mass % as calculated as oxides. The attachment rods are sized to be received into receptacles provided in the top of a vehicle seat designed for the vehicle headrest. The toothed rack has the shape of a circular arc and moves on a circular path upon activation of the drive unit.