Spectrum Chemical manufactures and distributes fine chemicals with quality you can count on including those with CAS number 1072-71-5, Whether you call it Bismuthiol I, 2 -5-Dimercapto-1 -3 -4-thiadiazole or 1 -3 -4-Thiadizole-2 -5-dithiol you can be assured the Bismuthiol I products offered by Spectrum, meet or exceed the grade requirements or specifications for each individual product.