Thumb Score: +20 Walmart has 12" ZINUS Ultra Cooling Gel Memory Foam Mattress (King) on sale for $269. Shipping is free. Thanks to Community Member Penguin_Dude for finding this deal. About this Item: [LIST][*]General Note: Please allow 24 - 72 hours for your Mattress to regain its full shape. Any memory foam will expand faster in a warmer room.