The Lifeline GPL-3100T is specifically designed for the rigorous cranking demands of marine industry engines and generators. All Lifeline cranking batteries are hand-made in the USA. These batteries are built using the same high standards and proprietary methods that are employed in the manufacturing of similar aircraft batteries for the US Military. They are designed to deliver ample cranking power when it is needed most and are perhaps best known as industry leaders in reliability and customer satisfaction. Lifeline cranking ratings are provided using the Battery Counsel International requirements which dictate each test run for a 30 second duration. All Lifeline cranking batteries are backed with an industry leading 5 year warranty.