This bag is an excellent example of Tom doing his thing: watching how people use a bag, and figuring out how to improve that experience. 

The Aeronaut/Techonaut Packing Cube Backpack basically replaces/serves as a Large Packing Cube: it's designed specifically to fit the main compartment of our Aeronaut 30 convertible travel bag, but works well in the Techonaut 30, and A45 or T45. It helps you organize and compress your clothes inside of your larger travel bag, maximizing the space inside of your travel bag and keeping your clothes neat and less prone to wrinkles. 

When you arrive at your destination and turn it right side out, the Aeronaut/Techonaut Packing Cube Backpack all but sprouts wings and flies. A small top compartment appears, adding four liters of storage space—great for your camera, lunch or other smaller items. This compartment also has a flat front pocket with a diagonal zipper for storing quick access items: sunglasses, lip balm, sunscreen. Into the 10 liter main, lower “cube” part of the pack will go your bulkier items like books, a sweater, and rain coat. Depending on the size of your water bottle, you may choose to store it in either compartment.

Included with the Aeronaut/Techonaut Packing Cube Backpack is a fully-removeable 1” / 25mm Gatekeeper Waist Strap: if you don't like or don't use the waist strap, remove it and leave (almost) nothing behind.

You may want to hang on to that waist strap, however, as it's an essential component in transforming the Aeronaut/Techonaut Packing Cube Backpack into a waist pack or sling bag: inside-out the whole pack into the top compartment, attach the waist strap to the webbing loops sewn into the side seams, and secure the bag around your waist or wear it cross-body. (Note that the empty main “cube” portion of the pack will now be scrunched up inside this top pouch/waist pack, so it won’t quite have all four liters of volume available to store your stuff.) 

The waist pack or sling mode is useful if you’re headed out for some shopping: as you accumulate food or souvenirs or what-have-you, you can right-side-out the whole thing again, giving yourself the full backpack to carry your treasures back to where you're staying. Or, if you depart in the cold morning hours for a hike carrying the Aeronaut/Techonaut Packing Cube Backpack in waist or sling pack mode, you might like having the space to stow your peeled-away layers in the full pack as the day warms.

The Aeronaut/Techonaut Packing Cube Backpack features a 1” / 25mm webbing carrying/hanging loop on top, simple 2”  / 50mm webbing shoulder straps and a removable (in this case think also dual-function) 1” / 25mm webbing waist belt. It does not feature a padded back, a padded hip-belt, an internal frame, nor a solar-powered convective cooling unit.