Polyolefins are being increasingly used in the outdoor environment where they are required to provide improved life cycle. Polyethylene film is increasingly used for agriculture in glass houses, while Polypropylene moulded products are used in furniture, automobile and other sectors. Polypropylene fibers are used in bags for industrial packaging. This increased usage has been made possible due to developments in UV stabilization systems. These systems are essentially developed through Hindered Amine Light Stabilizers (HALS). Most of the HALS are developed around Tetra Methyl Piporidinyl property. There are several types of HALS with different chemical structures, molecular weight and molecular weight distribution. These variations are responsible for performance behavior. Additionally solubility, volatality and diffusion parameters of HALS in Polyolefins provide variations in performance against ultra violet radiation. The chemical structure around Piperidinyl has been evolved from Polyamino groups and Polyesters to Triazine. The introduction of Triazine chemical structure has improved performance of HALS. It has been observed that molecular weight of about 1500-2000 of an Oligomeric HALS has optimum performance compared to lower and higher molecular weight. At the same molecular weight, MWD (molecular weight distribution) plays an important role in performance behavior.