This product is a novel phosphorus-based auxiliary high-temperature antioxidant with a high effective phosphorus content and excellent hydroperoxide decomposition capability. It exhibits outstanding initial color stability, high transparency, and superior flow properties. Commonly used in combination with hindered phenolic antioxidants, it is widely applied in ABS, PS, HIPS, NBR, SBS, PP, PE, LLDPE, PVC, PC, PA, PET, UP, polyamide fibers, polyester fibers, adhesives, coatings, and inks, as well as in the production and processing of composite additives, ethylene-vinyl acetate copolymers, and calcium-zinc stabilizer systems. The product features a bisphosphite structure with a high content of alkylated trivalent phosphorus, significantly enhancing its antioxidant performance, ensuring superior stability, and delivering exceptional oxidative resistance under high-temperature conditions.