The Back-Roller Core is the solid base bag among the Back-Rollers and yet 100% waterproof. With its robust polyester fabric, it's not only suitable for extended bike tours but also ideal for daily urban commutes. With the Back-Roller Core, you're always ready to transport important items dry and securely - whether it's on your way to work, shopping, or other urban adventures. A reliable companion that withstands the elements and simplifies your everyday life. If the basic functions of the Back-Roller Core are ever insufficient, this practical bag can be expanded with various optional accessories. The Carrying System Bike Pannier helps carry the Back-Roller Core on your back, various inserts provide stability to the bag body off the bike, or offer better organization inside the rear bike bag. FURTHER PRACTICAL DETAILS - High-visibility reflectors on the outside of the bag.