20Ah for 23 bucks? Seems like it's almost too good to be true. Wouldn't surprise me if it was just half that, would explain the price and weight.
replies(8):
https://www.amazon.com/DCHK-10000mAh-Charging-Portable-Motor...
https://www.amazon.com/DCHK-20000mAh-Charging-Portable-Motor...