If I remember correctly, these are the ones that play nicely with the Sawyer Squeeze water filters (because matching threads), and possibly present a more durable/ideal solution compared to the bags Sawyer packages with the Squeeze.
To expand on the Sawyer bags based on personal experience: I've noticed that they have rather thin walls, which aren't very abrasion resistant. They are also rather rigid (almost crinkly) and have somewhat sharp edges at the bottom, which frequently results in the edges getting caught in/tearing the mesh pockets of my pack. Being opaque is also something of a disadvantage, too - I'd like to be able to see how dirty or not dirty the interior of the bag is. Something I have not experienced, but have read a few reports of on the forums: busted seams resulting in leaky bags.
I'd be pretty happy to replace the Sawyer bags with something else, and the evernew bladders seem to be the only viable, non-rigid option on the market (that I'm aware of).