Although panniers are, in many ways, practical and a comfortable choice, there are still situations in which a backpack is the only way to go. Ortlieb developed this backpack to be just the perfect choice for bike commuters. The materials are, in traditional Ortlieb fashion, 100% waterproof and tough, all seams are welded tight and all together it's easy to guess this pack will stand up well to the rigors of daily use. The outer fabric of this model is of type "PS33," a material very common in Ortlieb products. It is completely waterproof and durable for everyday use. - 100% waterproof without a need for rain covers - Padded computer pocket inside, measurements 39 x 27 x 2.5 cm - Ergonomic shoulder straps - Back panel padding has generous grooves for air circulation - A non-waterproof small pocket with zipper - Attaching points for a LED light (light not included) and a U-lock (U-lock not included) - Reflective logo - Simple and highly durable roll closure - Reinforced bottom - Detac