Optima D31T YellowTop battery provides the extra performance and deep-cycling capability that your vehicle demands if it has a lot of accessories like running lights, high-performance stereo/AV system, winches, or hydraulics. The unique SpiralCell design provides a strong and clean power source, ensuring the safety of you, your family and the environment. The Optima battery is ideal for seasonal use because of its very low self-discharge rate. That means you can store your seasonal vehicles all winter without regular charging and still spring out of the starting block when winter is over. Case Material: Polypropylene.