American Weigh Scales Class M2 14-Piece Small Calibration Weigh Kit Carbon Steel with Chrome FinishRed

This set of weights exceeded my expectations for accuracy given the price point. I will be the first to say that the case on this absolutely sucks. The holders for the round weights aren't terrible, but the spots for the square weights below 1g really need to have a better cover. The stock cover for the holders doesn't cover the entire opening. As such, the smaller weights (especially the ones below 100mg) are prone to escaping from their compartment and flying around the case. The bottom part of the case is made from two plastic pieces glued together, but there is a gap between them. When I first put this set of weights away, I didn't know about this problem. When I opened the box the next time, the 1mg weight was mysteriously gone, and some of the other weights were scattered around the inside of the box. Low and behold, the 1mg weight found its way into the very bottom of the box, between the two glued plastic pieces. The only way I was able to retrieve the weight is via the assistance of a strong rare earth magnet (prying the box apart would have worked as well). I suspect this is why some other reviewers are losing their smaller weights. To avoid this happening again in the future, I designed a 3D printed cover that protrudes slightly into each compartment. The OpenSCAD code is at the end of this review. My piece printed slightly tight, so I would recommend scaling down by a few percent if you print this yourself. I'm also not entirely sure if it's necessary to run the cover down into each compartment - a flat cover might be perfectly acceptable. Now for the part of the review I'm sure most came here to see... the actual weight of each of these weights. To weigh these, I used my Mettler Toledo AE 260 scale. It is an older model, over 20 years old at this point, but it's still accurate and precise. There is a built-in 100g calibration weight, but I was worried it might have lost some mass due to corrosion over the years. I ended up buying a 10g ASTM Class 1 calibration weight, and my scale measured this as between 9.9999 and 10.0000grams after calibrating to the internal 100g weight. Essentially: the weights I have measured here are precise to 0.1mg, with the caveat that they are potentially up to 0.1mg less than the true weight, according to an ASTM Class 1 calibrated weight. The theoretical weight, and my measured weights are as follows: 50g: 50.0095 g 20 - 19.9976 g 20 - 20.0016 g 10 - 10.0052 g 5 - 5.0014 g 2 - 1.9983 g 2 - 2.0011 g 1 - 1.0015 g 500mg - 499.9 mg 200 - 200.0 mg 100 - 100.5 mg 50 - 50.0 mg 20 - 20.0 mg 10 - 10.0 mg 1 - 1.1 mg As you can see, the actual weights are relatively close to the listed weights. They're not perfect, and off by quite a bit when compared to many international standards. That being said, these weights are not meant for high accuracy lab work - they are meant for a home user. Although I'm sure there are some, I'm not presently aware of any home applications where a 10mg error at 50g is a deal-breaker (honestly, this is even perfectly fine for a lot of general lab applications). As long as potential buyers of this weight should are aware of the intended user base, I think this a great set. I personally just use this to verify my scale is reading in the right ballpark across its entire range, and for that it's great. Of course I would prefer a full set of ASTM I calibrated weights with a nice case, but I don't want to spent $500-$1000 on a set of weights. For anyone reading this review, please note that the weights listed above are for my specific set of weights only. I can almost guarantee your set will be different. What you're paying for when you buy an $80 ASTM calibrated weight is the guarantee that it will definitely be within 0.xxx mg of the specified weight. With this cheap set, all you are guaranteed is that the weight will be within a few percent of the specified weight. Some will be nearly perfect, but many will be off considerably. OpenSCAD code for replacement lid: module indentations(){ cube([14.5, 20.5, 5]); translate([16.25, 0, 0]) cube([13.5, 20.5, 5]); translate([31.5, 0, 0]) cube([13.5, 20.5, 5]); translate([46.75, 0, 0]) cube([12.5, 20.5, 5]); translate([61, 10.5, 0]) cube([7.75, 10, 5]); translate([70, 10.5, 0]) cube([7, 10, 5]); translate([79, 10.5, 0]) cube([5.75, 10, 5]); translate([86, 10.5, 0]) cube([5.75, 10, 5]); translate([93.5, 10.5, 0]) cube([5.8, 10, 5]); translate([61, 0, 0]) cube([14.5, 8.75, 5]); translate([77.5, 0, 0]) cube([10.1, 8.75, 5]); translate([89.5, 0, 0]) cube([10, 8.75, 5]); } translate([0,1,0]) indentations(); translate([0,0,1]) cube([99.5,23.5,5]); translate([25,5,3]) cube([8,12,10]); translate([67,5,3]) cube([8,12,10]);

Today the American Weigh Calibration Weight Kit, Class M2 arrived in the mail. I measured various GRAMS to determine how accurate was my RCBS 5-0-5 scale is. To say I am amazed is an understatement. Before you use it for reloading, I would suggest going online and finding a "Grams to Grains" conversion calculator. I'm not sure if this will post, but I used: [...]. The kit comes with 2-20 gram weights. On the conversion website I entered the 20 grams and the equivalent number is 308.65 grains. I measured 308 grains on my RCBS scale and then placed the weight on the scale - it was near perfect. Remember the equivalent is 308.65 and NOT just 308. So to make a long story short it was PERFECTLY ON. I then removed the first 20 gram weight and placed the second 20 gram weight on the scale to test the weights for consistency. It was dead on the same amount WITH NOT EVEN A SMIDGEN OF VARIATION. I then did it with all the other weights as the 50 gram is tool large to measure with this scale, but every weight was not close, BUT PERFECT!!! For a precision reloader this is a great way to keep your scale accountable. :-) When I weigh a load, I want my cartridges to be as perfect and consistent as possible. Also because of the inherent danger of loading too much powder in casing is dangerous to both the firearm and myself, this little inexpensive tool gives me the peace of mind to know that I am right on because my scale is extremely accurate. Every reloader should own one. For only 12 bucks, you get a great resource that keeps you safe and consistent. Sure the plastic tweezers are not the best for placing the 20 grams on the scale, but if you are delicate and careful when picking the larger weights up, it is possible as I didn't drop a weight once. For all you exactitude people out there, THIS IS A MUST HAVE!

Awesome value, useless tweezers, sadly missing the 100g weight that would make the kit complete. I bought a 100g weight hoping i could modify the box to fit it into the space that seemingly was made to fit it so that i could have a complete set that I could use to calibrate my new 200g scales. (both of which need 200g but one of which needs both 100g and 200g) I used a razor knife to separate the inner frame from the box, pulled out the inner frame from the box, then i used a forstner bit size 7/8 to drill the bottom out of the 100g spot. The foam in the lid was too tight for the box lit to close w/o distorting it so i used a 5/8 fortner bit turned backwards by hand on the foam to cut a nice circle, using the same trick i cut a circle in a piece of smooth cardboard and pressed down on the foam so the cut circle would 'pop up' through the cardboard and used an extendable razor knife to slice off about 80% of the thickness of the foam; now i have a complete set including 100g individual weight and enough other weights i can easily calibrate my two 200g scales. I managed to 'tiddly wink' one of the 20mg weights across the room and lost it and am pretty sure the kit came with a 5mg weight that went missing on first use; so word to the wise be very careful opening the ziplock bag with the micro weights! My new scales have 0.01g precision and all the weights appear to be well within 0.01g tolerance as i've been getting exactly repeatable measurements. the mg weights could be made better and with consistency (e.g. all stainless steel so they won't disappear in the presence of a magnet) and it would be *really nice* considering the size of them and the negligible cost, that there might be some spares! That said it would be a solid 5 stars if it had the mystery 100g spot filled with a 100g weight and if the tweezer included wasn't pointlessly useless (wouldn't open enough to pick up the 5g weight and broke when trying to stretch it open big enough to do so, also wouldn't grab the mg weights so really literally useless). Super happy on the purchase and would most definitely buy again. (and modify again and through out the useless tweezer again)

Can't complain about a set of calibration weights that cost less than $20 and are within ~.002 grams. The storage box is perfect, if not overbuilt, though it's not meant to be tipped over. The tweezers are good for anything below 5 grains, and everything 5 grains and above can be manipulated with my fingers anyway. I zeroed my scale using the included weights and checked each one and found only one that was over +/- .003 grains, and it comes in at +.005 grains. For me, this won't matter since I will record each of these weight variances in both grams and grains. Glad I bought this set and wish I hadn't sat on the fence for so long because of the negative reviews. The only problem I found was the little nut on one of my weights was backed out pretty far. This meant I had to take an Allen key set out of the drawer, find the one that fit, and tighten it back down; so glad I made it past that trial. Want a better calibration set? spend 1.5k more and get one that is certified.

Arrived with the case broken in two places even though it was well packaged, so it must have already been broken. All the weights were included, but the two 2g and the 1g weights were bare metal, while the rest of the gram weights were chromed. These three were also slightly underweight, perhaps because of the lack of a chrome layer. However, all the weights except the 5g were within tolerance limits for the M1 class even though they are advertised as being accurate within Class M2 limits. (My scale measures to thousandths of a milligram, and is reputedly extremely accurate based on ratings given here at Amazon.) So at least this particular set of weights is better than advertised. I don't really have a need for the milligram weights, but they are all there. The box is a nice design, with slots for even the tiny milligram weights with a little lid for that section of the case - although it does not lock down. Even the tweezers work surprisingly well. It is too bad that the type of plastic used for the case shatters so easily, because that is the only drawback to this set.

First off, Love the kit, used it a few times to check the accuracy of the scales I bought online, it has all the weights to check many scales. used it to calibrate the scales of a few business friends of mine, Great buy and strongly recommend this. Now for the downside, the Case is a POS as it sits. I also purchased the 100 gram weight separately to fill the empty hole. Thought it odd to sell it separate, until I got it home and tried to put it in, I see why, it won't fit. the problem is the cheap molding process, the insert has a 'bottom' for the weight. Now for my fix, for the largest hole 100 gram, got my dremel or any small rotary tool with a small cutting bit on the tip and cut out the 'bottom' or shelf on the insert, careful to Not go thru the outside case. Carefully cut around the outside edge at the bottom of the hole and it will lift out. this is a 2 part case glued together, but they forgot to cut out the insert. This is taking me longer to write it then it took me to do it. The weight fit almost perfect. Only thing left is the foam on the lid, press the lid closed a few moments and see the imprint, cut this out with the rotary tool. All done, Fits pretty good now. Takes about 10 minute to do this job. Now the little cover for the real small weights is not well designed at all, I got a scissors and a bit of Velcro, not too pretty, but it works. The weights are Great, but the case is not. But I still recommends this.

Just got this M2 weight set in order to feel better about my new $20 scale, which claims to weigh to 100g with 0.01g precision. I am skeptical of the quality of a lot of your cheaper consumer electronics so I figured it was worth the extra 50% to feel confident in the scale. The plastic case is solid enough to last me for years. It has a reasonably durable hinge, a good clasp, a firm foam lining with holes for the larger weights, an extra "hole" for a 100mg weight if you want to buy one, little pockets for the tiny weights (which are snips of metal with numbers stamped on them), a clear plastic cover for the group of little pockets, and, possibly my favorite, a pair of plastic tweezers that are curved on one side so you can always press one end to get at the other end with your bare fingers. I love this whole setup because I don't need expensive "industrial strength" cases for most of my light-use tools like this one and this set is packaged so that I can use it as-is on a permanent basis. Hilariously, the tweezers were packed with the curved side up, so I had to get a pair of helper tweezers to get to the tweezers. Perhaps one of the casualties at this price point is staffing the assembly line with people who hold master's degrees in test and measurement. I love it. Five stars.

The calibration kit is a good value for the money. As pictured, you get a bunch of different weights in a case. I checked the larger ones on a 0.1g resolution lab scale and they read XX.0g each time. If i get access to something more accurate, I'll update the review to reflect this. This is a class M2 product, which provides decent quality for the non-professional user. If mass is very critical, much higher quality/accuracy weights are available, like ASTM level 1 or even Ultra class calibration weights. You'll pay $100 for EACH of those weights, so I can't be too critical of a $20 set, ranging from 1mg to 50g. The larger weights all have a set screw in the bottom, so it does look like some adjustability is allowed during manufacture/calibration of these weights. The only real disappointment is the crappy case. Everything fits, but the sides are warped, which is even visible in the product shot on Amazon. This calibration kit won't impress anyone in looks, but seems to be doing the job in terms of accuracy for my home usage. I recently bought an inexpensive scale that reads in 0.01g increments. The weights all read their rated values, within the 0.02g tolerance of my cheap scale.

No testing certificate inside, or label about rating or tolerances on the outside, unfortunately; but my analytical scale likes them and that's what matters. Box kinda sucks—edge of mine was a bit broken on arrival and it has a number of unoccupied slots—but a Mr. Rogers teaches us, it's what's on the inside that counts. Hence, full marks.

Liked it

Un excelente producto para mantener calibrada tu gramera/báscula y que debes tener sí o sí. El material del que están hechas se siente de buena calidad y su peso es exacto al que se visualiza.

Great product and prompt deliveey service. The weights are precise and of good quality. Thank you for your services.

Cumple mis expectativas