When you're travelling, you don't want to lug your rucksack or suitcase around all the time: it's far better to leave it at the hotel, hostel or campsite and take a daysack with all you need for the day. The Eurohike Packable Daysack folds down into its own stuff sack for easy packing in your luggage. It has a 16 litre main compartment with a dual zip.