Stabilizers protect polymers from thermo-oxidative and photodegradation, extending the service life of products made from PP, PE, PVC, PS, and elastomers. Two main classes: antioxidants (primary phenolic — radical scavengers, secondary phosphite — peroxide decomposers) and UV stabilizers (HALS — hindered amine light stabilizers, UV absorbers — benzotriazoles). Without stabilization, polymers yellow, lose strength, and crack. Dosage: antioxidants 0.05–0.5%, HALS 0.1–1.0% of polymer weight. Synergy: a combination of primary + secondary antioxidant is more effective than each separately. Packaging: 25 kg bags, boxes, drums. Synergy: combination of Irganox 1010 (0.1%) + Irgafos 168 (0.1%) provides protection during processing (extrusion, molding) and in service. For outdoor products: HALS + UV absorber (benzotriazole). Storage: dry warehouse, protected from moisture and light. Shelf life 24 months. Manufacturers: BASF (Irganox/Irgafos), Songwon, SI Group. Documentation: CoA, MSDS, TDS.