This actually gives me an idea for an excellent suggestion that I hope Chris or Dan will pass onto Vision to consider.
At this time, I don't see any variable volt ( or wattage ) PV units that take the visually impaired or the blind into consideration.
The Spinner looks to be an excellent candidate to address that with... All it would require would be a series of raised bumps at each voltage location along the bottom ... and making certain that the red line on the dial is either raised or inset well enough that a person could feel it with their thumb or finger. The raised bumps could have a single bump for the lowest voltage setting, two bumps for the next highest and so forth... possibly a raised line for the last and highest setting.
I probably wouldn't have even thought of this had it not been for my mother needing to pick out a cell phone that she could use again since her macular degeneration had progressed to a point that she now can't even read most of the larger print found on most phones. She just needed a basic phone with separate raised buttons she could feel the difference between them... and some other basics like some one touch dialing so she could call her most important numbers.
The Spinner ( or even the Twist ) with the addition of a few raised bumps to help tell where the voltage setting are at would be all that a visually impaired person would require.