Umpqua Steamboat ZS2 Sling Pack, The Steamboat ZS2 Sling carries like a fully supported backpack leaving your line-of-sight and range-of-motion free upfront. Perfect for spey or switch fisherman. A thumb loop allow for easy "slinging" from back to front for quick access to essentials. A large main compartment easily holds a light rain jacket, lunch and boat box, while a secondary face pocket is great for accessory organization and smaller boxes storage.