124-64-1 52221-67-7 55818-97-8 Bis(tetrakis(hydroxymethyl)phosphonium) oxalate EINECS 257-753-5 PYROSET Flame Retardant TKS Phosphonium, tetrakis(hydroxymethyl)-, ethanedioate (2:1) (salt) Pyroset TKS Tetrakis(hydroxymethyl)phosphonium oxalate Tetrakis(hydroxymethyl)phosphonium oxalate (2:1)