(Telecompaper) Amazon has unveiled the latest version of its Kindle e-reader, offering a light, slimmer model that comes with a charging cover. The Kindle Oasis is now available for pre-order for USD 289.99 and will ship in the coming weeks. The dual-battery system sees the accompanying cover charge the battery in the reader automatically. The battery in the cover uses a custom cell architecture that optimizes power and energy that delivers "months of battery life", Amazon said.