eBay with EcoFlow Official Store has the refurbished EcoFlow DELTA 2 1024Wh Smart Generator Extra Battery (ZMR330EB-BP) for $436 - 20% off with coupon code EFAUGSALE2 [Exp 8/17] = $349 with free shipping. This is an extra battery of the DELTA 2 Power Station to expand capacity to 2048Wh.