2-Naphthalenesulfonic acid, 7,7'-iminobis[4-hydroxy-3-(2-phenyldiazenyl)-, sodium salt (1:2); 2-Naphthalenesulfonic acid, 7,7'-iminobis[4-hydroxy-3-(phenylazo)-, disodium salt (9CI); C.I. Direct Red 31 (7CI); C.I. Direct Red 31, disodium salt (8CI); Aizen Direct Rhoduline Red BH; Amanil Rhoduline Red B; Atlantic Brilliant Red 12B; Atul Direct Red 12B; Azine Fast Red 12BK; Belamine Fast Pink G; Belamine Red 12B; Benzanil Rose B; Benzo Rhoduline Red B; Benzo Rhoduline Red BA-CF; C.I. 29100; Chloramine Rose B; Chlorazol Rose B; Colonal Red 7B; Cresotine Pink 3B; Diacotton Rhoduline Red B; Diamine Rhoduline Red B; Diaphtamine Red 12B; Diazamine Fast Purpurine; Diazol Rose R; Direct Brilliant Red B; Direct Pink 12B; Direct Pink 3B; Direct Pink EG; Direct Red 12B; Direct Red 31; Direct Red M 12B; Direct Rhoduline Red B; Direct Rose RW; Direct Safranine RW; Enianil Fast Brilliant Red 12B; Erie Brilliant Red 12B; Fenamin Red B; Kayaku Direct Rhoduline Red B; Libia Red 12B; Mitsui Direct Brilliant Red B; Nippon Fast Red BB; Phenamine Rhoduline Red B; Pink 12B; Pontamine Red 12B; Tertrodirect Pink DR; Vondacel Red 12B