Throwing it out there; I have a Bonfus pack, and I like it a lot! But for some added comfort that I can easily put on or remove, I grabbed a Ventapak attachment. It is this lightweight spacer that goes between the user's back and the bag; creating space or a gap for airflow - they are less than 1 lbs in weight, which I know is still a stretch for gram weenies, but I like that it can add variety in comfort for different bags that depending on the wearer may want more air flow on their back. If someone struggles with sweat on their backs after purchasing a pretty expensive bag, the Ventapak attachment may be worthwhile at not a terrible price or weight! Also after looking at some reviews for the Ventapak, they have had older issues with some of the clips not being up to snuff, BUT reviews have consistently stated that the company sent replacements as needed and have since updated the buckles in their newer Ventapak products to limit the weak buckles. So another good company to support <3