EDIT - STARTS TODAY (24th):
Just had a black friday heads up email from Anker where the price of the PowerCore 20000 will be dropping 25% from £34.99 to £26.24 (calculated based on the email saying 25% off).
The BF promo will be running for a week from 24th Nov to 29th.
Don't think its a code, think it's just being reduced.
This is a whopping 20000mAh which can charge an iPhone 6s 6 or 7 times ultra fast.