Whenever possible, I try to buy products made the the USA over foreign imported products. Made in USA keeps Americans working and it usually implies a quality product. I recently purchased an E-Z Red hydrometer for my car battery and also one for my car's coolant. I can't speak for the accuracy because at present I don't have a reference to compare them to, but the build quality is not very impressive on either of the E-Z Red tools. Also, the float on coolant hydrometer tends to stick and I have to shake the tool until I think it is where it is supposed to be. I know how to use these tools, but for someone who is not familiar with their operation they'll have to use Google for instructions because there are none included with either tool. I have a refractometer coming which I plan to use as a reference against the E-Z Red hydrometers. If there is a discrepancy, I will update this review.

Does the job.

This hydrometer works. Don't know how accurate it is, but it is better than nothing.

The product seems like it is built well enough take day-to-day use and abuse. If you are just using it to get a ballpark idea of the state of charge for individual battery cells, it works great. For automotive battery troubleshooting, it's probably good enough. If you need to know a battery cell's state of charge to something more precise than ~5%, however, the scale likely won't be incremental enough- there are big jumps, particularly at the high end of the range. The Hydrovolt may be a better choice.<br /><br />The other issue I had was that it has to be held level to be accurate; there is a level marker on the back of the scale, but it is often obscured by the float and its large meniscus in use.

I bought this hydrometer to check 12 batteries on my off-grid solar power system. Not sure I like this tool. The price is right and I may use it as a spare. I am unsure how well this unit measures the specific gravity. I ordered a nicer German made hydrometer, I'll be able to check for disparity in the measured acid specific gravity.