Deuter ACT Zero 50 + 15 Pack ENGINEERED WITH INNOVATION - ACT Zero trekking packs bring together all around versatility and advanced ergonomics for optimal comfort and performance; Distributes weight effectively so you can go further without discomfort AIRCONTACT LITE SYSTEM - A body contact back design keeps weight close to the body for effective load transfer with breathable padding made of open cell hollow chamber foam and an anatomic X-frame of aluminum stays ADJUSTABLE - Vari Quick adjustable back length fits torsos between 14 and 19 inches COMFORT & STABILITY - Ergonomic Comfort Lock hip fins of dual density foam custom fit by adjusting to each wearer for load stability EXTRA ROOM - Extendable 15L pack collar with optional roll top closure; Removable 15L lid converts to summit pack