ONE YEAR review!
Having used this one for about a year - stepping down from 220 to 110v - in my experience, it works great. It's reasonably well built (of course, I opened it and inspected it before entrusting my devices and my home's safety!). There are a few soldering points that could have been cleaner, but nothing is outright loose or cold-soldered. The transformer is toroidal, machine-wound, of course. The voltage readings are close enough (there is a way to calibrate, but it's very rough tuning, which I did anyway against my Fluke). One other thing I wished it had from the factory, which I added, was a bug screen. I hot-glued some on the inside for added safety. Just to add, in case it's not self evident: this is a voltage converter and it does NOT convert frequency so be sure your appliance can take both 50/60hz as typically 220-240v comes at 50hz and 110-120v is produced at 60hz.