Primero movement. Zenith offers the Chronomaster chronograph watch in nine variations including the Chronomaster Open El Primero, Grande Chronomaster Open El Primero, Chronomaster T Open El Primero, Chronomaster T Open El Primero Sun Dial, Chronmaster Grande Date El Primero, Grande Chronomaster XT El Primero, Grande Chronomaster GT El Primero, and the Chromaster T.