I received my Amazon order for two of these chargers and I immediately tried them out. Each one can be powered in three ways: 1. Mini USB cable. 2. 4.5 V DC power supply. 3. 2 AAA batteries. When you use the AAA batteries, only four of the LEDs will light up. I don't know how well the four LEDs charge a solar watch because I only tested my chargers with the batteries to make sure that the battery terminals were making good contact. I never ran them for any length of time with the AAA batteries. For the long term test, I powered my two chargers with one of these Vivitar USB chargers that has two 2 A USB outputs: https://www.amazon.com/dp/B005GCMYAG/ref=cm_cd_asin_lnk Note that if you plan on getting a dual USB output charger similar to what I bought, look carefully at the current output through the two USB ports. I found that most of the units do not have a full 2 A output from both USB ports. Most of them have 2 A from one and 1 A from the second one. Ideally, you want as much current as possible (2 A) from both USB ports. The Vivitar one that I mentioned above was one of the few with that option. Despite what the Amazon reviewers said, I have had absolutely no problems with the one that I bought. The solar watch LED chargers are made from very thin black plastic and they are very light weight. I would not even think about taking them on vacation with me because I don't think that they'd survive bouncing around in a suitcase. They are plenty durable enough for what I intend to do with them though - sit on my dresser and charge up my Casio, Seiko, and Citizen solar watches once a month. I put two of my most favorite Citizen Eco Drive dive watches on the new chargers: my Eco Zilla and my Promaster Aqualand Depth Meter diver. Both watches rested on top of the chargers' rubber bezels without extending beyond the bezels' outer edges. The chargers' rubber bezels are great because they did not scratch my watch bezels. The LED chargers worked great! I have never run my solar watch batteries down very far (that will shorten the life of them) but my depth meter dive watch has a power reserve meter on it and it was down to about 75% charge before I started my test. After about three hours on the LED charger, the meter was up to a full 100%. Even though my two watches were fully charged up, I decided to leave them on the LED chargers for a full 24 hours. After sitting on the chargers for the full 24 hours, my watches were only a little bit warm and not dangerously so. This is a major benefit to using these LED chargers versus leaving solar watches on a windowsill where they can really cook. Also, unlike sunlight, LEDs do not give out UV light so they will not fade watch dials and hands. Fading hands is a big problem with some Citizen Eco Drive dive watches with bright orange minute hands if they are left on a windowsill repeatedly for recharging. The chargers come with two different sized rubber bezels. Supposedly one is for woman's watches and one is for men's watches. I only used the larger one for men's watches and it worked just fine. It was able to accommodate both my largest watch (the 50 mm Aqualand Depth Meter BN2021-03E diver that I ran my first test on) and my smallest watch (a 40 mm Citizen BN0000-04H diver.) Both fit just fine though the larger watch rested on the highest top surface of the rubber bezel, while the smaller one fit down low inside the bezel on its sloped/inclined surface. All of my other solar powered watches in between those sizes fit just fine on the chargers. When resting my large Aqualand Depth Meter and Eco Zilla watches on the chargers, the bumps on the surfaces of the bezels caused the bezels to not sit 100% flush against the chargers' rubber bezels all the way around. Those gaps between the watch bezels and charger bezels let some of the light from the LEDs shine out and into my bedroom. My wife complained about the light on the ceiling last night when she was first went to bed but after she shut her eyes, she fell asleep in a few minutes. She slept just fine throughout the night so the light spilling out from the chargers may seem like a lot at first, but once you close your eyes you won't notice it. My smaller watches like the 40 mm Citizen diver I mentioned before that fit within the bezel did not have nearly as much light spill out. Also, in theory, a watch bezel that is perfectly smooth will rest completely flush against the charger bezel and prevent any light from shining out and into the room. None of my solar watches have smooth bezels so I did not get the chance to test out that theory. So I give these little solar watch chargers two thumbs up. For what they are, they're not the cheapest things out there, but if they keep my solar watch batteries from going dead and keep my watch hands and dials from fading, they're a great buy. Some of the negative comments/reviews for these solar chargers say to just leave solar watches on a window sill to recharge them. Here is my reply to that idea: Putting a solar watch on a window sill exposes it to lots of UV light. That harsh UV light can fade the dial and hands if they are brightly colored, as are the minute hands on several of my solar diving watches. There are pictures on the internet of badly faded dive watch dials and hands from people that made the mistake of using a window sill to recharge their watches. Unlike sunlight, LEDs like what are used in this charger do not give out a lot of UV light (some sources say that LEDs do not put out any UV light) and thus they will not fade anything that they illuminate. Also, if you have a Citizen Eco Drive watch, the instructions clearly state to avoid charging the watch in an area that becomes hot like a car dashboard. A window sill in direct sunlight can easily become just as hot as a dashboard. Too much heat is not good for the movement in solar watches. Of course, you can just wear a solar watch to recharge it (unless you're nocturnal) but when you're a watch collector, usually you have too many watches in your collection and your solar ones only come up in the rotation every few months at most. As a result they don't get the necessary wrist time to sufficiently keep their batteries fully charged between the times that they are worn. Letting solar watch batteries die repeatedly will drastically shorten their life. As others have found out the hard way, these chargers will not fix a completely dead rechargeable battery in a solar watch.
