[Photo Forum Moderator]
The brand of electronic dry boxes that I have are from "Toyo Living"
the box is plugged into house power and it runs a small device that removes moisture from the air.
There is also a blue light that runs continuously.
Too dry is just as bad a too moist... target for camera equipment is about 35% RH (relative humidity).
I have had the smaller box (41-50 L) for over 10 years... works like a charm
The larger unit I just purchased (Toyo Living ED-120CATP2(B) Auto Clean Dry) is the same brand.
Because of a capacity issue I have been using three sealed plastic boxes with moisture packets... they
work well, but need to be checked often as the packets only last a limited amount of time (better than no solution).