While looking at some photos found this, thought might interest somebody.
Symetrik, Endura and Endura Symetrik. There is some speculation that those marked Endura where for export, the straight Symetrik isn't common and while the same size as the standard streamline Endura Symetrik it doesn't have the inlaid cresent in the cap and a slightly smaller nib (the caps interchange) so a lesser model