This hydration pack features a 15-liter gear capacity and includes a 2-liter lumbar-positioned reservoir designed to help maintain balance during activities like mountain biking. It's constructed from durable ripstop nylon with a water-repellent finish, making it suitable for trail use. The pack also offers multiple compartments for tools and essentials, along with a breathable mesh foam back panel for comfort. It is very cute and compact but can fit a lot of stuff - no wasted space. Like new! Tried it out around the house but never took it on a hike or bike ride. Ended up sticking with my Flash 22. Let me know if you have any questions.