BCIP Pink (6-Chloro-3-indoxyl phosphate, <i>p</i>-toluidine salt) is a derivative of BCIP chromogenic phosphatase substrate. While BCIP yields a blue precipitating product, BCIP Pink produces a pink colored (&lambda;_max 540 nm) precipitate. This kit contains 100 mg each of BCIP Pink and the oxidant NBT (Nitro blue tetrazolium), which facilitates precipitation of the substrate.