Anna frost hard rock pack mod?

Hello all,
Saw this pic from hard rock and was wondering if anyone has an answer as to what this is. Interested to add poles to my sense ultra set and wondering if other people have done the same. Here is the photo. Looks like some sort of upper elastic sewn to the top of the pack??

https://pbs.twimg.com/media/CJpYO9lUAAEeh6k.jpg