Received very quickly, just a few days after ordering. Bought 2 of them and both compared almost perfectly to the voltage measured with my Fluke VOM. Power the meter with the small Red And Black wires. Measure voltage with the same Black (neg) wire used to power the meter and the Yellow wire to measure the positive voltage.

Great product. It's a bit small, but for the price I don't think that's a valid complaint. Functionally, it does everything it says it does, and it's pretty accurate as well, according to two separate DMMs I tested it with. I wired this (the 7-in-1 multimeter version) up to a 750mA battery charger, just to give me some feedback on what voltage and current the charger is putting out at any given time. As a bonus, it also lets me keep track of exactly how long the charger has been on and how many Ah the charger has theoretically transferred into the battery (although, of course, batteries are not 100% efficient at storing the energy you put into them when charging, so that really only gives an upper limit). I also love that the display can be powered by anywhere from 4VDC to 20VDC, which meant that I could just pull out a random wall wart from my big box of abandoned wall warts, strip the wire ends and hook it right up. No need to go hunting for one with just the right voltage output. I will likely be buying more of these in the future.

Meter works. I have some concern with the voltage drop across the shunt, since the shunt must be in the negative supply line, which raises the ground reference of the logic a bit. The concern is that it will cut into noise immunity. So far, this isn't a problem.

Be careful when hooking it up. Follow the wiring diagram for the particular installation you need for your circuit.

Great little display for the price. Perfect for my application. I connected the display to a pressure sensor installed on my Koi pond filter system to indicate the degree of filter pluggage. Over time, the filter clogs up with debris and the filter inlet water pressure increases. This translates to an increase in voltage on the display. Instead of guessing when to flush the filter, I can monitor the voltage. The display is mounted inside the house and I can see the voltage (pluggage) increase a couple of millivolts each day. The extra decimal place on the display is very useful since I am tracking a fraction of a volt. Starting voltage with a clean filter is about 0.650 volts. The filter requires flushing when the voltage reaches about 0.850 volts.

UPDATE: Well, I have been corresponding with Drok about their lack on instructions.I got a card with this meter saying they were a small growing company and wanted reviews/feedback.

I told them that I had gotten it working by accidentally seeing the wiring diagram in the pictures on the product page. They said:
"We are terrible sorry for any inconvenience caused you.
We are sorry that we don't have user instruction for some of the DIY semi-products.
However, all information you can find on the Amazon description page.
And if you have any questions, just feel free to write back us.
Can we refund you $5 as compensation for the trouble caused you?
Beg your forgiveness and hope you could understand.
Best regards"

When I replied to that and told them that I had gotten it working, the said that I was "clever". Maybe they are hiding the instructions to see how many "clever" customers there are.They gave me a partial refund for my "troubles" and offered me the opportunity to update my review. So, I am doing that now.

Bottom line, the product seems to work great once I got the wiring figured out (IT IS NOT INUTITIVE). Without the diagram, you will NEVER get it working (for example, the thin black wire is not used in my configuration). They don't include the instructions (Just print them off and stick them in the package). The company is obviously a foreign company (Pacific Rim). Their English (or lack thereof) is obvious. So, I am updating my review, but I am NOT increasing beyond 3 stars (probably should give them less for their apparent lack of interest in improving their product support with instructions). Was their company Drok or Dork?

Yes, it came with ZERO instructions. However, on the product page there are several pictures. One of the pictures shows various wiring options. I wired mine up with the last option and it works great. I would give this a 5 star rating, however, I am lowering it to 3 because it was such a hassle to try to figure out how to wire it up. IT IS NOT INTUITIVE. Yes, the vendor needs to include the wiring diagram with the product. If I hadn't accidentally found the picture, it would have been going back.