EXcap 120 is a set of optical reference normals for verification, adjustment or calibration of Exner NIR backscattering sensors. This set can be equipped with up to three individually selectable single normals to verify the corresponding sensors in their ideal measuring range. The reference normals can be easily attached on to the measuring window, so that they are optimally fixed during verification or calibration. The normals are traceable according to NIST standard and can be verified at the factory.