My earlier version CVI is 4 1/8" tall when using the 18350 battery. Does that help?
My actual "controller" portion with connector is 2 1/8"
I believe the Zmax/Seigeli (sorry about spelling) is a bit shorter and the Prothingy mini a bit shorter than that.
I checked the site and it looks to me like V1 and V2 are the exact same size. If you get one, go ahead and get the 18650 tube as well for when you want an 18650 lighter weight
mod.