Snugpak Yoke System Packs & Bags attaches to the side pockets of the Rocket Pak and the Bergen Pak to allow the user to create a small and versatile daypack. This creates a great system and can be easily stowed and packed in the Rocket Pak or Bergen Pak with all your other gear and deployed when needed. When the two 915 Cubic Inch (15 Liters) side packets are attached you have a small and agile 1830 Cubic Inch (30 Liters) daypack.