R-phycoerythrin Labeling Kit-SH is for simple and rapid preparation of R-PE-labeled IgG. SH-reactive R-PE (a component of this kit) has a maleimide group and can easily make a covalent bond with a sulfhydryl group of the target molecule without any activation process. The filtration tube in this kit allows a quick buffer exchange and concentration of sample IgG solution. This kit contains all the reagents necessary for R-PE labeling, including the reducing agent for preparation of reduced IgG that has an SH group and the storage buffer for conjugates.