It stabilized the voltage pretty exactly.. the issue with just transformers (step up / down) is that if the input voltage is slightly higher, the output voltage is too.. but here it doesn't matter.. the output voltage is either 120V or 230V.. it also doesn't matter, if the load is just a few Watt or the full range.. it stabilizes load independently..

I really like it.. don't waste money by buying just a step-up / step-down generator.. if the voltage is out of specific of your connected devices, they get damaged..

So a clear buy!!

I've bought several of these units in different sizes/amp output for use in Europe. These units, out of the box, appear to click uncontrollably from what I surmise is coming from an internal relay; my guess without opening the thing up to investigate. There is no rhyme or reason when the condition starts or stops with or without load; sometimes this unit will work without the chatter while at other times I cannot get it to quit.
Update: In the spirit of running it to failure, I found that the more use these regulators get, the more they "calm down" and do not clatter as much. With this particular model, we use it to run our 110v microwave, crockpot, Instant Pot, toaster, and rice cooker...individually of course.

Longevity: It has been almost 11 months and the clicking clattering has somewhat subsided and these units have not failed. Also, if you have newer line protection circuit breakers in your house, you may find this will trip them upon initially energizing; no load attached. This condition doesn't happen all the time, but enough to make note of it.
Pro Tip: If you are in the market for voltage regulators, be sure to check the wattage on the appliances they will be used with to gauge the correct size needed. Also ensure that when you energize the regulator for initial use, your load is disconnected or turned off; I.e. Power up that crock pot AFTER powering on the regulator. ;)

I bought a 3000 watt and a 1000 watt just to see if I thought they would do what I needed. Although I wont know for a few more months how well they actually do work, they seem to be just what I needed. We are moving to the Philippines where voltage is not regulated so well at times from the local suppliers. We want to take many of our 110volt things with us, and I will be taking many many portable power tools I have. I tried both of these here at home by putting 220volts into them and to make sure they would start motors with surge at start up, the 3000 watt one operated a 15 inch miter-box and everything else in lower wattage I tried with no problems.

We are tacking a freezer, a fridge, and some kitchen appliances along with quite a few electronics, because good quality stuff there is very hard to find, but everything is 110volt, so need to step it down from 220 volts, just hope these will work ok on things like refrig. and freezer which need to be 24/7/365. I will go oversize with them and hope they wont overheat like some have said theirs have done.

My only complaint was the packaging from Amazon, it was pathetic. These are kinda heavy items, and they along with a plug strip were all put into one way too big box with no cushioning material at all, so they had destroyed the plug strip and had also destroyed the boxes the transformers were packed in, but the transformers themselves were ok.

I need to order quite a few more of these in various wattages, but think I will order them one at a time so hopefully they will pack them in smaller boxes with some cushioning materials in them.

UPDATE:
I bought 9 of these in sizes from 1000 to 5000 watt so we could use them to power 120v items from 220v source. We used them for small kitchen appliances, electronics and small power tools. None were ever left turned on except when being used for one or two hours at a time typically. I bought extras because I figured they would quit working and I was really right on that. In my opinion they are garbage they do not last long. Burned up one today that was just usedforthe first time charging an 18volt Milwaukee battery. It has been plugged in for no longer than 10 minutes when it started humming loudly and stopped working. It was a 3000watt size so no way it was overloaded with a small battery charger. I think I have 2 left of the 9 , one 3500watt one worked for over a year but all the rest had a life span of less than 60 days some less than 30 days. I would never buy another of this brand they are a pure waste of money, extremely bad quality.

I can get them rebuilt here in Philippines using good quality parts and they last pretty well but they just replace everything inside them with new parts and only use the meter and on, off switch.

The unit now works well and I am very pleased with the value for money, but I had some initial issues with it. First was the two pin US plug, had to buy a VCT Electronics VP13 adapter for it to be properly grounded. Second was that it was DOA; some quick fault finding identified a bad connection in the fuse on the front panel (easy fix), but during this fix noticed that the majority of the sheet metal screws that secure the cover had stripped threads and required new bigger screws on reassembly.

In short, it is true stabilized power supply that works very well, it is a really good deal, but the QC and the 2 pin US plug need some attention.

Vintage electronics usually only operate on either 110V (120V) or 220V (240V). I feel more confident using this regulator to power my vintage electronics with a consistent regulated voltage. Still, to avoid any potential accidents with the wrong voltage, I've labeled the vintage machine's AC/DC plugs just in case.

Pro: This voltage regulator has a nice retro look-and-feel. Perfect to power vintage electronics. The voltage regulator is very quiet, but not completely silent, with an almost inaudible 60Hz hum. The instructions are translated to English with a few typos, which is alright. Just follow the steps described. Beware that the input voltage selector on the back of the unit must be set to the voltage supplied to the unit, which may not be entirely clear from the instructions.

Cons, a minor one but may matter: The AC lead to the unit has a standard European grounded plug. A US-EU converter plug is supplied to power the converter from a US socket. This converter plug has no ground pin, which would have been much better to ensure the unit and output are properly grounded when powered from a grounded US AC socket.