I have been looking at these for a long time and have almost ordered several times. I would like to know the length of the Vapor Zeus 650 not counting the threads? How does it compare in length to the DAV 650 Auto? Length matters. I think you should make a version of the Zeus if you got rid of the USB charging port. Keep the USB charging option on these that want it but some of us want the length per mAh to be as small as possible. Keep the 14mm diameter but reduce the length. I know some will use the USB charger but others will value getting the length down more so. The reason I also have not get the DAV either is the added length. Regulated fixed at 5 volts is a good number for a portable set up. Eliminating the USB port and not getting one with VV will do much to get the size down and I think you would have a world beater in portable 14mm devices.