I bought it for 1200 tk and used it for 2 days. I don't need it anymore so I want to sell it. If anyone needs it, you can take it for a fixed price of 600 taka.
20000 mAh power bank can charge a 5000 mAh phone 4 times fully. I was outside Sylhet for 2 days and used it, now I don't need it anymore.