Optima D34M BlueTop is designed as a dual purpose battery, both starting and deep cycle for people who need a sure-starting, strong cranking, and maintenance free power source for their boat or RV, even in harsh conditions. The unique SpiralCell design provides a strong and clean power source, ensuring the safety of you, your family and the environment. The higher reserve capacity gives you a longer shelf-life to give you the power when you need it, where you need it. This battery is designed to be used with recreational vehicles or boats with large accessory loads.