Devices for measuring the profile of the thickness of press felts and molding meshes PMM on the width of the canvas, the measurement data allow you to assess the state of the wool, their compaction, wear, and also predict the life of the wool. The results of the measurements do not depend on the material, humidity and temperature of the cloth (sieves). Instruments allows directly on the operating paper machine to determine the spectrum of fluctuations in the mass of the paper web in the machine direction. Analysis of the spectrum makes it possible to determine the sources of fluctuations, such as vibrations of press rolls, vacuum oscillations on the mesh table, and others. In addition, the device allows you to evaluate the quality of paper forming.