"Combined 2 years" The key word is "combined". That instills a lot of confidence. So if you had 12 Zs running it for 2 months that is 2 years combine. Let's see it last 2 years or more on the same car(s)in 110+ degree weather? That is the real long term test. No need to get defensive. The battery may look pretty, but how long will it last? There are a reasons why batteries are rated in months of operation.