I purchased this to measure the voltage on an variable voltage controller that uses a lamp dimmer. While the description was clear that it would measure in the 80 to 300 volt range, I somehow failed to grasp that concept. Imagine my disappointment when I plugged it in while the controller was set to a low voltage and it didn't measure... Imagine my joy when I cranked the voltage to the full range of the controller (100 volts) and then lowered it to about 10 volts. I connected a hand held volt meter to the circuit and to my pleasant surprise the Yeeco tracked with the hand held to within a volt over the 10 volt to 100 volt range. This thing worked great for me. What a satisfying purchase experience.

have had it plugged in for 8 hours, does not get hot.Voltage displayed updates regularly unfortunately seems about 5% off (about 5 volts low as per my Fluke volt meter) Good enough to tell me voltage is in the line.

Was concerned about reports of power fluctuations from a neighbor. Plugged this in and glace at it occasionally as I go about my day. Easily viewable from across the room. (No problems with my power noted so far.)

Pretty much what I expected. It's backlit, all the time. So if you want a nightlight it's perfect. Probably don't want it over your bed though. Quite happy with it.

Simple little tool works as it should

Simple to use

The unit is smaller than I expected, but I am good with that. It is off by about .5v, which can be adjusted according to the write-up. Does work well as a nightlight. Keep in mind, in an RV, this will only read one of the two incoming legs for voltage. If you want to monitor both legs, you will need a second meter.

We kept having power spikes and rolling 'brown outs' in our house. Power company made me pay for an electrician and they said power company. I got tired of fighting with power company with no proof. So I bought this and when the lights flickered I jumped up and started video on the gauge. It was at 70v and spiked to 140v!! I called out the power company and showed them the video, they had nothing to say. I won and now we have a new service line going in to fix the problem. Well worth the price to help my sanity.I now keep it plugged in just to make sure they take me seriously until the repair is finalized!Pic is where the victory took place, just like a booth review with the NFL !

This is a very nice little AC voltage monitor that can be easily calibrated (see below). I bought two so that I could see both legs of my household power supply at the same time, and they have been plugged in for two months, now.I am using the 80-300 VAC model to monitor the 120 VAC supply in my home. When they arrived, they both read several volts too low. As someone else already mentioned, these higher voltage units were probably calibrated at the factory for 240 VAC and it would not be unusual for them to be a little off at half that voltage.This was easily corrected in a couple of minutes by opening the cases and calibrating them against accurate DMMs.To do this, make sure the unit is not plugged in. Then use a small ( #0) Phillips screwdriver to open the case. Cover the AC plug blades inside the box with electrical tape to make sure nothing contacts them while making the adjustment. Plug the unit into an extension cord (with three outlets on one end) so that it is positioned conveniently. Set the DMM to the appropriate AC voltage range and plug the DMM probes into another outlet on the extension cord head. Use a tiny (2 mm) blade precision screwdriver to carefully adjust the tiny potentiometer inside the unit (immediately behind the V character on the display) until its reading agrees with the DMM. Unplug the unit, remove the tape over the AC plug blades (or not), and put the case back together.The back of the case can be rotated 180 degrees so that it can be plugged into the top or bottom of an outlet and still be right-side-up.Things to consider: 1. I found the adjustment instructions in Product Description section of the Amazon page to be backward – turning the wiper on the pot Counter Clockwise makes the meter read higher, and vice-versa. Watch out for roundoff errors – 118.7 VAC on the DMM should show as 119 V on the voltage monitor, and so on. 2. It will not be easy to get the voltage monitor to increment to the next whole number at exactly the xxx.51 reading on the DMM. 3. The exact voltage reading on the DMM will likely be wandering around quite a bit due to loads changing elsewhere in the house and/or neighborhood as you try to adjust the voltage monitor. So after each adjustment of the pot wiper, watch the meters for a minute to get a sense of where the voltage meter increments versus the reading on the DMM, and adjust it again accordingly. Note that motorized equipment (with brushes like vacuum cleaners and drills) and some other equipment running on the same AC circuit may put enough electrical noise on the line that the voltage monitor may show a value that is higher than it really is.If you are not comfortable working in a little box with house mains voltage inside of it, note the voltage reading on the monitor, unplug it, make a small change in the position of the pot wiper, plug it back in, and compare the reading with the DMM. Repeat as needed.Calibration such that the DMM reading is a volt or two either side of the voltage monitor reading is easily obtained, and is most likely good enough.