The Arkray Bilirubin Total & Direct Reagent Kit is used for the quantitative determination of both total and direct bilirubin in serum samples. It is a diagnostic tool employed in clinical laboratories to assess liver function, diagnose jaundice, and monitor liver diseases or bile duct obstruction. The kit provides a reliable method for measuring both conjugated (direct) and unconjugated (total) bilirubin, aiding in the evaluation of various health conditions.