To add to this, the original Aromamizer, (no reason to buy this now), and the V2, (improved V1 in every way), are ~23mm in diameter, while the Supreme is 25mm. This may or may not matter to you,
@rcalvy1. I prefer the V2 to the Supreme because I can use it on my Pico, as well as my other mods. Also, the V2 is much less expensive than the Supreme.
Ymmv.