This document provides instructions for the use of the Rat Ferrochelatase (FECH) Enzyme-linked Immunosorbent Assay (ELISA) Kit by Uscn Life Science Inc. Wuhan. The kit is intended for in vitro research and is not for clinical diagnosis. The document includes information on the kit components, storage and expiration date, experimental principle, collection and storage of samples, and preparation of reagents.