X, I think it was seamless tube. The battery operates fine off of an alternator. I bought the battery in early 2017. They said it should last up to 10 years. After October 2018, I didn't try to use it again until mid 2021. It wouldn't hold a charge. I called them, they said send them the battery. After testing it, they said I should have had it on a charger more frequently for long term storage. I think I charged it once or twice in the 2-1/2 years. They offered me 40% credit on a replacement due to the battery being over 4 years old. I thought that was fair enough. The battery I bought from them in 2017 was an ATX-20 with 720 CCA. I used the 40% credit on an upgrade to the ATX-20-HD to get the 900 CCA, even though the old one was enough. It wasn't that much more $, especially with the 40% off. The new battery will get charged monthly when in storage! Hoping to get 10 years.