The Wilderness Systems Lithium Battery refines the kayak battery beyond the heavy and cumbersome marine batteries of the past. Lightweight and water resistant, the Lithium Battery not only excelsin form but in function as well with multiple output options, superior efficiency, power and amp hours. The compact design conveniently stows in most kayak hatches. Important, please read: " Wilderness Systems Lithium Batter Product Memo" below under "Product Documents". This product is not available to ship until April 2018.