The Ortlieb Back Roller Urban (sold individually) has a roll-top closure that, along with the durable tarp-construction of the bag, makes it fully waterproof. Differentiating the Back-Roller Urban from the Classic and Plus is the Urban's soft herringbone material. While still waterproof, it has the appearance of a more formal fabric like tweed. It has a large capacity if desired (40 litres) and can be unfurled to allow those carrot greens or a bouquet of tulips to billow out the open top. The Back-Roller's easy-on, easy-off QL2.1 clasps allow it to be secured to or removed from a rear rack with a single hand.