I picked this up after seeing it in the "frequently bought together" section of the EasyAcc 15000mAh battery pack and thought "a little extra protection for a bank of Li-ion cells is always a good idea". Well, it wasn't until after I received both items that I realised that further down the page had a "suitable for x, y and z" - basically up to the 12000mAh pack.
So, here's the deal. It *does* fit the 15000mAh pack, but it's snug (very snug, if you have any of the extra cables in the mesh pouch). The only other problem is that I understand the 15000mAh is physically longer than the other batteries: so you cannot have a cable plugged into the battery and it still be in the case (well, not without deforming the case and potentially damaging the USB sockets).
Despite these issues (which are really caused by me failing to read the product description properly), I'm giving this product five stars as it seems to be of a solid enough construction that I'd be happy to leave it banging around in the bottom of a bag - which IMHO, is the point of a case like this.