With the PartSens 4.0, PMT presents a portable measuring system with a wireless measuring head for fast and direct determination of particulate contamination on surfaces made of. As a Plus model, the measuring device additionally enables the differentiation of particle sizes and particle numbers of metallic and non-metallic particles as well as fibres on surfaces. The use of grazing light technology according to ISO 14644-9 produces reproducible and highly accurate measurement results. Complex sampling by gas extraction is eliminated, as are subjective measurement methods (microscopy) or error-prone multi-stage procedures (surface rinsing through filter media with subsequent filter analysis). The measurement result - including the live image - is immediately shown on the device display via wireless transmission. For archiving or for later comparison measurements, the data is stored in the particle counter, which can then optionally be output via an external printer.