Material and protection Constructed from 1000D polyester with a waterproof PVC layer on both sides for reliable water resistance. Built to be durable, tear-resistant, wear-resistant and heat-resistant to protect your belongings in daily use. Modular 3-in-1 design Includes 2 single-sided shoulder bags plus 1 backpack that can be used independently or together as a rear pannier system. Versatile layout lets you switch between backpack, shoulder bag, and pannier configurations to match your trip. Easy installation and compatibility Quick-release mounting system for fast attachment and removal on the rear seat pannier rack. Designed for convenient on/off use during stops or transfers. Capacity and dimensions Backpack: 19.4" L x 12" W x 5.8" H. Side shoulder bag (each): 11.7" L x 6.25" W x 13.7" H. Fully expands to increase carrying volume when needed. Practical performance Solid construction balances durability and lightweight portability. Waterproof PVC layers and rugged 1000D polyester help keep contents secure in variable weather and road conditions. Use scenarios Commuting: Attach to your rear rack for carrying a change of clothes, laptop sleeve, and lunch, then remove the backpack portion for walk-in access. Weekend touring: Use the full pannier setup for longer rides, then convert a side bag into a shoulder bag for errands or sightseeing stops. Shopping and errands: Expand capacity to transport groceries or gear, then detach a single bag for quick hand-carry trips. What you get A durable, weather-resistant, multi-function bicycle rear bag system with quick-release mounting and clear, high-capacity dimensions for flexible everyday use.