V1 looked just like V2, with a 3.3V - 6V variable range, and a 2.5A high current limit.
V2 raised the current limit to 3.5A, and modified the low voltage of the range to 2.9V - 6V.
V1 and V2 used identical bodies. For $20 ProVape can upgrade a V1 to V2 specs. All the coatings are Ceramic Coatings. On V1 and V2 they had the ProVari logo laser etched into the finish. The etched logos, especially on the satin silver color, would wear off over time.
V2.5 was an external design change only. The ProVari logo is no longer etched into the finish, it is now engraved into the stainless steel. The electronics for the V2.5
devices are the same as the V2
devices.
Pricing has never changed...