Fit & Design: Solid-fitting backpack built for weekenders and overnighters 55L is the smallest standard Aether backpack from Osprey On-the-fly shoulder and hip adjustments ensure a custom fit LightWire frame with a breathable Airscape back provides stability Durable water-repellent coating and included rain cover offer weather protection Compression straps ensure a secure load Zippered front panel gives you another way to access the main compartment Pocketing and straps offer storage for sleeping bags, pads, ice axes, trekking poles, water bottles, and more