The twentyfourseven plus 20 daysack is comfortable and versatile thanks to its breathable back system height adjustable chest strap and grab handle gym or walking gear and electronics or other gadgets are easy to place in and take out of the generous zipped main compartment and handy internal and external zipped pockets comfort and breathability in use is provided by a berghaus flow back system with vented foam with a height adjustable chest strap to dial in the fit just right storage opt