I'm new to the forum and Tom Bihn. The day has finally come for the arrival of my first Tom Bihn bag. I've ordered a Brain Bag (with brain cell, Freudian slip and snake charmer) along with an Aeronaut (with packing cubes). I went back and forth for 2 months on the Tristar and Aeronaut but liked the idea of one big compartment. I'm hoping I made the right decision. Can anyone tell me if there are O-rings in the Brain Bag or Aeronaut for pouches to attach to?