Thanks for the heads up, Ash, but, at least from the photos, I am very confident in its authenticity. The size, proportions, shaping, the beveling of the rim, the stamping are all dead on. It if definitely a Sasieni stem. Again, the shape, dot, and button are correct. The patent number 242513/25 is a Sasieni patent, but not the most common 150221/25. I'm pretty confident it's a winner!