revk, 
Hmmm.
As a consumer, if I buy a 10000mAh battery pack I would expect it to be able to provide 10Ah, i.e. 1A for 10 hours.
As this is 5V output, that is 50Wh capacity.
It seems, however, this is 37Wh.
So at the rated output of 5V, this would do 1A for 7.4 hours. It is, at the stated output voltage, a 7400mAh battery pack.
I can only assume the internal battery pack is 3.7V (typical LiPo). But that make the headline rating of 10Ah misleading at best.