Lowe alpine airzone pro 3545 backpack description a 4 season pack with space for extra winter gear this award winning hiking and trekking backpack features our unique airzone centro adjustable back system and adaptivefit hipbelt ensuring the best possible fit whatever your size the suspended airzone back system helps to keep you cool and the extendable lid gives you the option of adding 10 up to 10 litres of capacity with easy access side entry you can access your gear without having