Check the listing for details. MEGAWARE Battery Guard Shock Absorbing Protector Pad to Prolong Battery Life. Condition: New. Listed at 19.95 USD. Prolong the Life of Your BatterySave Money by Protecting Your Battery InvestmentMegaware BatteryGuard™ acts like a shock absorber and can help extend the life of your expensive battery. Excessive shock and vibration are two of the leading causes for battery failure. Megaware BatteryGuard™ sits under your battery and absorbs the gravity shock caused by excessive vibration and up and down bounce.Get the maximum performance and longevity from your battery. Reduces up to 80% of the G-shock Caused by Excessive Shock and VibrationGreat for Boats, Automobiles, ATVs, Trailers, or Anywhere Shock and Vibration Can Damage a BatteryDimmensions: 12¾” × 6⅞” × ⅜”Fits up to Group 31 BatteriesBattery G Shock Performance Comparison Scientific explanation: When a battery is subjected to extreme vibration and shock, cracks occur at the interface of mechanical joints inside the battery and its cells. While some batteries are designed to withstand these forces better than others, all batteries can be damaged by shock and vibration over time. Battery failure will often be preceded by performance fading. This is because the stress of shock and vibration causes micro fractures inside the battery which reduce internal conductivity and cause a battery to have low voltage. Over time, as the micro fractures continue to propagate in the battery’s conductive components, internal resistances increase. This condition reduces the flow of amps which are required to power electrical components. Another cause of performance fading is the physical collision of battery plates as a result of shock and vibration. This condition causes a short in a cell or cells. This also, may cause a battery to have low voltage and insufficient power. Note: Clamping the battery too tightly in place and compressing the pad may decrease the pad’s effectiveness. Caution: This product may excrete oil and stain certain surfaces and is recommended for placement in battery trays or boxes only. From the Inventor: “I am an avid fisherman and as an active participant in the marine arms race, I was frustrated by having to replace my batteries every year. After one event, I found my battery on its side and the strap broken. I realized that shock and vibration, far in excess of the batteries design specifications, was the probable cause. My solution was BatteryGuard; a pad that isolates the battery from the boat. Since their installation, I have never replaced the starting battery, which is now ten years old, and I have only replaced the trolling motor batteries once in that time period. The battery guard is the best solution to mitigate the destructive forces of shock and vibration. The original pads are still in my boat and still working as well as the day I installed them. They are impervious to water, oil and battery acid. When the problem is shock and vibration, BatteryGuard is the solution. It works!” Tom A. Versailles MO