It's expensive, but it's cheaper than on some other sites.It's waterproof, OEM, and extremely durable.I bought it as a failsafe in case my other Li-ion batteries go out.It's been getting harder and harder to find these kinds of quality materials at low prices.I rate it 5 stars for durability, but I'm not going to be using it as a primary power source.Buy OEM parts! The cheaper 3rd party equipment isn't as good and it only lasts a fraction of the time.4.75 to 5 stars.