Velcro attachment system. Elasticated around edges to ensure snug fit on any rucksacks. Complete with cord and cord lock to further secure the cover. Enhances the performance of your rucksack Elasticated around edges to ensure snug fit on any rucksacks Complete with cord and cord lock to further secure the cover Lightweight 100% waterproof ripstop fabric Velcro attachment system  Find More Snugpak Aquacover 100 Litres Backpack Rain Cover