The NANO-flex® II 180° DLS system measures particle size distributions of suspensions and emulsions in the range of 0.3 nm to 10 μm and concentrations up to 40 % by volume. The principle of heterodyne 180° backscattering applied here is characterized by its high selectivity in the nm range and a very high resolution; it is also suitable for samples with a wide or multi-modal size distribution. Due to the low penetration depth of the laser light, samples of high concentration are measured without disturbing multiple scattering.