These are amazing batteries, The IR is low (Not compared to Thunder power and Opti power that I fly in all my helis and planes) I now will be using these in all my smaller planes and park flyers. The C ratings are spot on and the Mah ratings are a little low. I have bought a now a fair bunch of these in 2 and 3S and they all have about 10 to 15% more capacity then rated, The 1000 2S all run 1100 to 1150, Keeping 20% in after the flight they will charge about 900 to 950. I had a custom built machine that allows me to check the C ratings on batteries and these all handle 29 to 32C so they are true to label even better then some of the higher end packs on true ratings. I fly Optipower and have for a long time in EVERYTHING and of course these packs will not preform with with them but look at the cost difference and these provide huge bang for the buck. they have no problem at all pushing out 25C constant and will handle more when pulling a constant 25 to 26C the 30C packs will warm up a good bit but nothing that is enough to get worried about. They really are a massive value for this high quality of packs at this price. I wouldnt trust them in high dollar machines but they have not given me a reason not to, I just trust Optipower when it comes to thousands and thousands of dollars in the air. Once again I have not been given a reason to not trust them. I will be buying more but the packs I buy will all be 2 and 3S and 1800Mah and under as I will not be using them in no helis or quads just small planes. I may try some in my really fast quads that I dont like destroying high dollar packs in a crash and these would be great for that, and ask any guy that flys really fast quads low and fast they do get smacked it pretty hard some times and thats 100% destroyed lipo, the quad is almost always fine other then props but the battery is almost always destroyed. (Posted on 9/30/2014)