Hi Z, Chad has already explained with a picture ~ the Heron's bottom is not our regular atty's type. It has wider threads on its periphery akin to the top-caps of 22mm mods* (M20/1 threaded ones), which enables it to flush mount (hybridized) on similar threaded mods, viz. Paps, Vela, Atom, Vanilla etc.
Tho in it's current avatar it'd not suit non M20/1 threaded mods ~ however, a proposed 510 Adapter (planned as indicated by Perseas), optional purchase, shall enable it to fit on anything in a short while.
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*Also could fit on the Paps-X (23mm mod) thru a X Adapter
I would be heartbroken if I didn't add a mod to your list of 20x1 mods as it is much nicer than a few listed...BCV Surfrider and XXIX are both 20x1 threaded tubes and are spectacular. I know there are others out there but for something as nice as a HERON to sit atop the mod, these definitely deserves to be listed.


I'm not good in english, but understood that immediately - just integrated that lovely word into my vocabulary