A cuvette suitable for use with photometric blood testing apparatus and the like. The cuvette includes a receptacle having flanges on either side having locating holes therein. The flanges are flexible to enhance the positioning of the cuvette. Single and dual cuvette embodiments are described. The invention additionally includes means for encoding a cuvette for optical detection thereof by means of multiple facets which reflect light passing therethrough molded integrally in the flanges.
