Goetland Certificated F1 Scale Calibration Weight Kit Set 25 pcs 1mg-1kg Stainless Steel High Precision for Balance Digital Scale Lab Education

Weights appear to be of high quality and accurate. I weighed them on an OHAUS Analytical Scale with readability up to 0.1mg. Before testing these weights, i calibrated my scale with ANSI Class 1 weights. On my scale, everything up to 5g was dead on accurate. The 10g weight was off by 0.1-0.2 mg, the 20g weight was off by about 0.2mg, the 50g weight was off by 0.4mg. These are definitely class F1 weights with everything up to 5g being closer to class E1 grade so these are nice weights for the money. they can be used to calibrate anything up to 0.001g but for the 0.1mg precision, you may need to step up a class to get the best calibration possible. I was not able to test anything higher than 50g because my scale only goes up to 60g. I Would assume that each successive weight after 50g has double the error of the previous weight. So a 100g weight would have an error of 0.8mg and a 200g an error of 1.6mg but again, I could not verify this. This is all to say that these weight are just as accurate as my ANSI Class 1 weights but at a fraction of the cost. If you are looking to calibrate a high end analytical balance than i would say that these weights would work for anything up to 5g. Going higher than that may throw off calibration slightly but if 0.1-0.5mg (0.0001-0.0005g) of inaccuracy is alright for your applications than these weights are for you and I wouldn't fork out hundreds of dollars on OIML Class E2 or ANSI Class 1.

The weights appear to be made from quality stainless steel polished to a mirror finish. Very little attraction to a strong magnet backs that up. I only have a very old but well cared for Mettler H10 analytical balance that measures down to 0.1 milligram. I can not use this scale to verify the accuracy of the weights but I can use the scale to compare weights to each other. The scale (when used properly) is extremely sensitive to minute changes in weight. Example 5 gram compared to combined 1, 2, and 2 gram weights. Doing several of these comparisons, paring up different weights showed absolutely no distinguishable difference. I know this does not verify the accuracy, but it shows that their relative values are very consistent. This suggests to me that they were carefully tuned and therefore are likely to be very accurate. I was only able to do these comparisons on the weights 100g and under as my scale maxes out at 159g. Overall this set is impressively high quality for the money. I don't normally write reviews but just had to share what a great value this is.

I like this set. It let me know my scale was good and didn't need professional calibration so it was well worth the money. I use my .5ml weight the most to test for accuracy of my scale.

Nice set for the money assuming it's as accurate as it claims.Tweezer are metal instead of plastic which could cause damage to the smaller weight. Comes with microfiber cloth.**NOTE** everything that isn't a number or 'g' for gram is in Chinese, so the certificate for this is somewhat suspect, and difficult to trace or verify. F1 without a traceable calibration authority is suspect at best. then again if you look up how much a "real" F1 set is, this is a great deal.

Tal cual lo requeria. Excelente presentacion.

ORIGINAL REVIEW: This could be a lot better. Product does not come with a certificate as indicated in the Amazon description. I was excited to find such a reasonably priced calibration set however that was based on it including a calibration certificate.UPDATE: Added 1 star. Again I bought this with the understanding the calibration certificate would be included. The seller contacted me regarding this product. While I appreciate them reaching out, their explanation did not really address my main concerns. Since contacting me it seems the seller has edited the description removing the mention of the calibration certificate. With that in mind, if you do not care about having calibrated weights this is a very nice and affordable set. Every weight has checked out in terms of accuracy and the case is convenient. I also appreciate the inclusion of a set of tweezers to manipulate the sub-gram weights. It would have gotten 5 stars had I known I was buying an uncalibrated set.

This set here is comparable to Rice Lake 12518 Metric Class F that sells for $351.20 which makes this a really great buy. Also better than Troemner 102898 which Amazon sells for $202. According to the description this set supposed to have a maximum tolerance of 0.005g at 1kg which puts it at 1000.005g and it actually weighed in at 1000.00g. This does have the kind of accuracy which they advertise it for and this could be what your looking for in terms of price.

You guys would not believe the accuracy of this thing. I’m an assayer at the laboratory, and I got these for personal use. I wanted to check their precision, and it’s incredible. I tested them on a microbalance, (1/100,000 of a gram) and most of the larger weights (1g to 20g) were within just a few hundred thousandths of a gram. I believe the 20g weighed out to 20.0002. That is literally 2 micrograms off. A VERY small piece of dust can cause that kind of variance.The smaller weights, in the mg range, appeared to be off further, percentage wise, but that is to be expected of such small things. Still the 1mg showed up as 1.992mg, only off by a few micrograms. Astonishing accuracy.