If you don't have a particular need/desire for displays, the notcigs Buzz Pro has been around since July 2011, excellent durability and performance, US made, great customer service. Their prior original Buzz was, AFAIK, the first production VV. The BP uses a very simple wheel interface, rotate it to adjust voltage up or down. Excellent regulation, it'll stay at the output you set right up until it's necessary to change batteries. Durability is tops, mine has had multiple falls of up to 5' onto concrete, other people have dropped them down shafts at work, one person even ran theirs over with a mower -- the tank on it was toast, PV fine..