5.1 ounces, and it doesn't include the battery pack, plus another 12.5 ounces for the Revolt 9000 battery pack.
And according to the specs on the page you linked to, it's only 13.5" x 38", not the size of a sleeping bag.
There are better ways to stay warm than this, I would think. I'd go for down clothing or VBLs (or both) before I'd consider this.
Edited by JustWalking (07/17/16 11:31 PM)
Edit Reason: Added dimensions