I have alot of Ovonic batteries, 4s, 6s, in all different mah sizes. They're always affordable and reliable, they have great power especially when I'm using them in my quadcopters. I had an issue with a set of bad batteries that I received and I reached out to Ovonic. A rep personally responded almost immediately and after explaining the situation they promptly shipped me new batteries and I sent them the bad batch to analyze. Overall I couldn't be happier with the batteries and the company overall. Very impressed.