BonvoisinAnalytical Balance 500 gram x 0.001g High Precision Lab Scale Accurate Scientific Laboratory Electronic Scale 1 Milligram Digital Jewelry Weighing Scale with Windshield (500g, 0.001g)

The performance is superbly good. Scale is more stable than even its own manual implies. I'm a scientist and regularly use for work 0.001- 0.0001- and even 0.00001- gram reading scales and analytical balances . I've written (non-published) tutorials and essays. Even concrete explanations of buoyancy correction and so on. This scale is a great 0.001-gram-resolution performer. The draft shielding however can very easily torque the surround plate and thereby effect a perturbation to the pan support and thereby obviously perturbing the force that is sensed (and thus the reading displayed). Just use the balance in a place without any draft and you'll be best off. If you DO use the draft shield be very sure that it mechanically is fully secured into ONE way it wants to go. This is not so easily done though. Battery operation works just fine. The accuracy is superb. (TECHNICAL: It seems that the 200-gram weight they perhaps purposely chose to be under 200 grams. Mine was 199.99546 grams. Never mind how I know. The point is that the scale will force this mass to be called 200.000. But this is good. A tidbit extra gain so that if you, like most folks, ignore buoyancy correction for weighing in air, then you'll be a little bit less wrong from the teensy bit higher gain: calling 199.995, 200.000 by the balance. Of course I have no idea what true mass your weight will be. And the value I gave was indeed true mass, not conventional mass value. And that term of art would need a couple of pages of explanation, as does buoyancy correction etc. ALL of which I am skipping.) So then: EXCELLENT performer. Quite accurate. Good resolution of 0.001 grams for its range (500 grams). EASY to use. The manual is well written too. AND the manual has excellent warnings -- even better than other "more serious" laboratory analytical balances give! That was a surprise. Value : Money ratio is outstandingly good.An example application. Frosted Mini Wheats is the ONLY cereal without tons of salt dumped in. (Skipping that topic, but it does amaze me.) So I like it. Then there was Mini Bites version: "half the size". Now is that half by mass (or volume) or in each dimension (which would give one-eight the mass). The scale used on 30 pieces apiece of regular Mini Wheats and Mini Bits Mini Wheats gave virtually exactly a 2.000:1 mass ratio. Half is indeed by mass. (If I measured with a caliper etc... could confirm cube-root-of-two or if not, then the mini bites pack the wheat threads... you get the idea. I'm a precise guy and a metrologist and so on. If I like this balance you definitely will. And there's nothing wrong with it being simple and easy. I would not use the draft shield if at all possible. And I would get the 200-gram weight provided analyzed for true mass. Best is indeed if it is a bit under 200 grams for TRUE mass. That way the teensy extra gain will give the displayed values being even closer to true mass even if you don't do buoyancy correction for weighing in air.For things like my cereal mini bites vs. full-size, this scale is a real pleasure. And perfect range and display resolution. Great for pills counting too. Many other uses. And very little money.

Works well

I've purchased this scale twice and both times the scale could not keep its calibration after a month or two of use. Incredibly frustrating. Even with the scale calibrated it wouldn't settle on a weight and then the weight would start to increase slowly.

Comes well packed in a foam lined box inside another foam lined box. 9V battery is required and a little hard to get fitted in the battery compartment. The balance measurement is steady once air currents and hands are removed from influencing the pan. The tare button once pressed stops the balance drift upwards after turning it on. It takes 5 min to stabilize. Excellent weighing technique is required to not cause the tare “zero” to change requiring a re-taring. I find weighing a three times reveals the balance will give the same number and return to zero if the pan is not bumped hard or the pan enclosure is not touched. I’ve left the right side panel of the enclosure off and the roof on with the roof’s hole closed. I can add and remove items without touching anything except the item to the pan using tweezers. This technique yields accurate repeatable results. I do have to use the tare more frequently than I’d like. The pan enclosure can too easily move which will always affect the tared zero point. I think that is a design flaw. I’ve put around 1 kg of weight evenly distributed on the roof of the pan to stabilize and secure it to the balance. That works well for me. Currently I am weighing air rifle pellets which average 15.89 grains. Weights vary only 0.01 - 0.02 grains if I follow careful weighing technique. Similarly, milligrams vary by 1 - 2 mg. For the price the balance is effective for my use. I highly recommend getting one or two weights from Troemner at the certification level required for your needs. A truly accurate weight set for this balance will cost several thousand dollars. A single weight will cost hundreds. I needed accurate relative weights, not absolute weights, so I elected for a cheap sub hundred dollar weight set with no certification.Update April 29, 2022: have found balance really needs about 5 min to warm up before the tare is truly stable. Recalibrating occasionally has been helpful too. Balance is still excellent for my purposes.Update July 9, 2022: The power adapter is the best way to power the balance. A 9V battery works for just a few hours. I found putting stick on rubber feet on the four corners of the floor of plastic enclosure fixed the problem either the enclosure affecting the tare. I no longer need to load the roof of the enclosure with weight. I turn on the balance, let warm up for 5 min, use the 100g calibration weight to settle the mechanism, remove and tare the pan. Then I’m ready to go. Awesome balance for the price.

Haven't fully utilized the product since I am only running it on 9v batteries. So far, accuracy is good as long as you don't have a lot of interference going on in the room you're working in. Best part is customer service. I live in asia and we don't have 110v outlets by default. They offered to send me a 220v ac/dc adapter for it to work without batteries and without me risking damage to the scale by buying universal chargers that come from unknown manufacturers. Great service!