In addition to the information about MW averages and distribution obtained with the RI detector, UV absorbance detectors may provide information about composition. UV detectors are used for polymers containing chromophore groups. Online light scattering detectors and viscometers provide information about the polymer structure. If a light scattering detector is used together with an RI, then it is not necessary the use of polymer standards to calibrate the equipment, since light scattering gives the absolute weightaverage MW (Mw). Light scattering detectors also measure the radius of gyration. Viscometer detectors also provide information about the intrinsic viscosity of the polymer and the level of branching (index of branching) of the polymeric chains. The more the number of detectors coupled to the GPC equipment, the more detailed is the structural and chemical information of apolymer that can be obtained.