Tuned for travel the AirPorter is a backpack travel cover to keep your backpacking trekking or hiking pack protected while in transit be it by taxi train or plane. Its lockable zipper provides added security and an improved shoulder strap makes lugging it to and fro a breeze. Small fits packs up to 50 liters in volume. Medium fits packs 45-75 liters in volume. Large fits packs 70-110 liters in volume.