In the beginning was the 27/64" (10.5mm) Sierra then Dayacom introduced the smaller and prettier Elegant Beauty with 23/64" (9mm) tubes then along came the Artisan Aero, the Elegant Sierra, the Sierra Elegant Beauty, the PSI Majestic, Majestic Squire and Gatsby, the Executive Sierra and the Lucida and Australiana EB from Timberbits and no doubt some copies from Rizheng all of which are variations on the same two themes.
There may be others I have missed or forgotten. Of all of these, Dan’s Zeta, having the smaller 9mm tubes most resembles the original Dayacon Elegant Beauty which was always one of my favourite versions of this style of pen. Looks like the quality is good too so I will definitely be in the market for some of these.
Another good choice of kit Dan.