Wasabi BTR NP-F960-JWP 7.4 Volt, 8500mAh, Amazon's Choice and four stars with 90 global ratings.
First test = 4292mAh
Second test = 4089mAh
Third test = 4353mAh
I disassembled the Wasabi pack to investigate further. The Wasabi pack has four unlabeled rectangular cells and a couple pieces of steel taped on top. I don't know the purpose of the steel other than to add a little weight to the pack. It serves no electrical purpose.