I just got mine in, one thing I noticed right away was how heavy the battery is in comparison to a normal 5000 Ma 4s battery. About 100 gr heavier, or 25% heavier. I know it has a circuitry and a case but that shouldn't add up to 100gr.
The circuitry couldn't come anywhere close to that.
One explanation would be that they're bumping the capacity a bit to get a more competitive runtime. The other might be a low end battery?
I'm interested to hear if other people observe similar differences.