This refractometer is one of the best purchases I have recently made. It is very easy to use. Just put three drops of coolant on the lens and look through the view finder.I have a bunch of vehicles and engines that have all been converted to using polypropylene glycol. For years I have been guessing about what the actual concentration of antifreeze is. When I received this I started checking and found that the concentration was anywhere from 63% to 25%. Now I can reliably adjust the antifreeze to bring it back to 50% where it belongs.

Very quick delivery.
Works fine. You need to calibrate it anyway with water and something known like 50/50 antifreeze/water so once you have done that it's accuracy is "close-enough" for a $25 instrument. To do better you need to spend in the $125+ range. IMO.
Comes with soft plastic pouch, screwdriver, piece of cloth, and pipette.
Also bought a package of 20 pipettes from Amazon for $1.52, delivered.

Seems to be spot on. Easy to calibrate. Good optics. Easy to use and much less cost than the one I've had for 20 years

Simple and Effective. My car used G12 which comes from vw undiluted. unless you do a full flush its difficult to know if your mix of glycol to water is correct. This tool made it simple for me to correct the mixture in minutes.

Came with; (1) Soft woven pouch with a small handle and belt loop, metal zipper, black (2) blue lens cloth (3) blue two sided instruction and maintenance guide with diagram (4) soft plastic pipet (5) small adjustment screwdriver (6) refractometer. Reticle is graduated and scaled for Ethylene and Propylene Glycol mixtures (also has scales in percent glycol in parenthesis) and Battery fluid Specific Gravity (also with judgement calls; recharge, fair, good). The hand "Feel" is solid, tad heavy like its mostly made of metal. The dual jointed sample cell cover flips back easily but feels sturdily attached. This is normally a delicate and expensive lab instrument, so you would expect it to be handled carefully. This one is the "Farenheit" scaled instrumented (Not the Celsius or Centigrade) be careful when choosing your purchase model. Perfect for USA and Imperial Measure countries. It is specifically calibrated for automotive fluids, so be very careful you understand it is Not a general purpose Brix or other type of Refractometer. The principles and usage are the same.. but the Reticle scale makes all the difference. It rather makes me think it looks and feels like a Star Wars Light Sabre .. so if you have kids be sure to store it carefully. I specifically took photos of it before I used it and through the Eyepiece with my Cell Phone Camera so I could post real photos of the actual unit as it came. I plan to use it soon. I put some filtered tap water on the sample cell and used it to look at a light source, it was solid white at the bottom right on the 32 (0%) line just as it should be. Very easy to use, very unambiguous to determine the reading.