Amazon has just released Kindle Oasis, its thinnest and lightest Kindle ever. At $290, it is also the most expensive Kindle in the line up. However you get a bundled charging cover at the price, which adds months of usage battery life to the Kindle Oasis. This compares with weeks of battery life for Kindle ($80), Kindle Paperwhite ($120) and Kindle Voyage ($200). The new Kindle Oasis also has a screen with enhanced lighting that uses 10 LEDs. Kindle Oasis will be released on April 27. You can pre-order one now.