I'm not sure there is such a thing (for sale). I've heard rumors that Cybervex may be coming out with a 5V Bartleby, but he's certainly not updated his
webpage to that effect.
I predict that 5V+ devices will be on their way out. I think Drew has really hit on something with his low resistance attys (used with his Magnum and Phidias Woodimus). Once he starts selling the attys separately (that's a hope, not inside knowledge), they will transform
vaping as we know it.
You see, it's not necessarily high
voltage that we crave, but 8-10
watts (i.e., power), which is based on battery voltage
and atomizer resistance (measured in ohms). watts = volts X volts / ohms.
And there have been too many exploding mods (using unprotected and/or stacked batteries). A low-resistance atty on a high mAh
true 3.7V battery (e.g., 18650 or even 14500) should knock your socks off.