They are worth $5.99. They aren't worth much more than that. Whether they are good enough for your application is a judgment call for you. They won't give you as many amps as the higher end batteries, and they won't last as long as even the $20 batteries. I personally think that Gens Ace batteries are a better buy. They give you more amps therefore more power, and they last longer. The other issue with Zippy is that they have no quality control whatsoever. There are lots of threads about Zippys being DOA, around 1 in 5 in seems. Then the lifespans are very variable. Some people have 2 year old Zippys that still deliver usable amps and full capacity, and some (like myself) have had to toss them after 6 months because the internal resistance went up so high that the aircraft couldn't fly with them anymore. So all of that is to say that if you want a lot of batteries and you don't care how long they last and you want them cheap, Zippys make sense. Buy 5 of them for $30 plus shipping, expect to throw 1 away immediately, and expect to throw them all away in less than a year. Or you could buy 2 Gens Ace or Power Wing batteries for about the same money and get better performance and likely twice or even 3 times the lifespan. It's your call.