Fine posing by Mirjam in an early example of the great work by the Silhouette designers. The very first Silhouette glasses had no serial number stamped on the arms. A few years ago, the company kindly fulfilled my request to provide the year of manufacture for two dozen Silhouette glasses in my collection. This enabled me to extrapolate the age of the vast majority of their other glasses. Their information indicates that serial numbers were introduced around 1970 and that these metal glasses were made in 1973 or 1974.