I decided to test the capacity of these batteries side by side with an identical CR1220 name brand Renata battery. The picture shows the resulting graph. The BlueDot battery tested at 44.9 mAh whereas the Renata tested at 40.4 mAh at a 2.0v cutoff and 10200 Ohm load for both cells. That's about 10% greater capacity in these cheap cells vs the quality name brand batteries. That's impressive! Around 40 mAh is a very respectable capacity for these tiny batteries. However I am still a little skeptical about the BlueDot batteries. They may fall behind a little when it comes to self discharge rate so their shelf life may be shorter than the name brand batteries. This is only my own speculation. I have not tested the self discharge rate because the only testing method that I'm aware of is simply storing them for a period of time then testing their capacity as compared to a fresh cell. Maybe ill revisit this in a year. Anyway, these are good batteries at a reasonable price, especially if you purchase the bulk packs.If you are a Makers teacher looking for batteries these are a great find. We build all sorts of paper circuits with them, and it was a whole lot of fun. All of the batteries seemed to work with no issues! The CR1220's are smaller and easier to place than the bigger 2032's.So many kids toys and all have different battery sizes, these works well, thanks amazon for having awesome prices!So far so good. Couldn't believe how had it was to find a replacement batteryvyet how easy to find on Amazon.Use them, work wellThey have all worked as expected, however it's only been a few months, so we'll see how long they last.Fits what neededThese were approximately $.23-.24 per battery.I may have been unlucky and got a lemon, but ALL the batteries in the package came in with around 1V of charge level (instead of advertised 3V). Needless to say, the batteries cannot power the thermometer I wanted to use it with. Looks like the package was on a shelf for years.Avoid and choose another brand/distributor.These were the correct battery, arrived on time. Sadly what we wanted them for broke, so now we have lots of batteries that don't fit anything else :(all good!