The ISO40X system performs an accurate on-line surface density analysis (weight per surface unit) along the cross section of the mat being examined. It is also possible to measure lengthways, selecting a point on the mat where the scanner can be positioned automatically. The analysis is conducted without any contact with the material by exploiting the X-ray control theory and the use of non destructive testing techniques. The solid state crystal receiver, the “state-of-the-art” in terms of X-ray receivers, consents rapid measurement data acquisition and consequently a much faster mat scanning speed with respect to standard systems.