Ray,
The link you provide lists the 10,000 mAh version as 222g (7.83 oz) in the paragraph up top under “Product Packaging.” If you select the 5,000 mAh version it lists the weight as 120g (4.2 oz).
I do see that under specifications at the bottom under “Product Information” they list 4 oz for the 5,000 mAh version and 4.8 oz for the 10,000 mAh version, but I would suspect the numbers up top are more accurate — i.e. 7.8 oz vs. 4.2 oz.
Have you weighed your battery on a scale? Perhaps you have the 5,000 mAh version. I would be very surprised if the 10,000 mAh battery weighed in only 0.8 oz more than their 5,000 mAh version.
