The product is recommended as a highly efficient & colorless UV absorber for plastic materials, particularly engineering plastics such as polycarbonate and polyesters. Eusorb UV-988 which is a benzylidene-bis-malonate type UV absorber with pronounced absorptivity in the high energy (low wavelength) range of the UV spectrum, shows a significant improvement of long term stability of PC. In addition to the stabilization of PC, Eusorb UV-988 also can be advantageously used to improve the light stability of PET to UV light yellowing and brittleness may occur. Eusorb UV-988 would be the good choice of UV absorbers if the maintenance of transparency is required. To meet performance requirements of PC, the suitable UV absorbers should be critically choosed. However in some cases when exposed to more demanding climatic conditions (heat, UV radiation, water…) even stabilized PC parts still continue to exhibit discoloration such as yellowing. The mechanism of this failure can be explained by the photodegradation of some UV absorbers as shown as bellows leading to the loss of the UV protection followed by discoloration.