Check the listing for details. Onos Swamp Cooler Spare Rechargeable Battery Power Bank For USB Models. Color: Black, Condition: New. Listed at 35.00 USD. This listing is for a rechargeable power bank that is compatible with ANY of the USB model units for sale in my store. This power bank gives you the freedom to take your USB model Swamp Cooler off grid and anywhere you like without needing to plug it in to work. How does it work? Simple plug in your power bank and charge it fully till you see 4 blue dots.Unplug from charger cord and take to your USB Model ONOs Swamp Cooler.Plug Swamp cooler into bottom port on Power bank.Turn on Swamp Cooler and your out the door.How long will the battery last? For a single fan USB Onos Swamp Cooler a full charge of this power bank will give you 6-8 hours run time depending on what speed you run unit fan on.For a dual fan USB Onos Swamp Cooler a full charge of this power bank will give you 4-6 hours of run time depending on what speed your run both fans on.Power bank holds 10,000 mAh, 5N 2.1A of portable battery. Charger cord for power bank included with purchase.ANY questions just ask. This listing is for Power Bank ONLY...Onos Swamp Cooler is not included. This listing is an accessory for USB model Onos Swamp Coolers ONLY. Free shipping within the Continental USA. Please take a good look at all pics and ask questions before you buy if need be. Additional shipping fee required to ship to AK, HI, PR & GU