Timbuk2 Designs Especial Tres Cycling Backpack 2014, Black, One Size A high volume weatherproof roll-top pack for serious cyclists Durable Cardura nylon fabric Dual side stretch pockets fit water bottles or U-lock Dual side stretch pockets fit water bottles or U-lock. Features a waterproof rolltop plus swing around side access to the main body of the bag. Internal organizer for pens, phones, and other small stuff. Backbender flexible cooling panel for superior ventilation and comfort. Backpack straps feature high density foam with cooling mesh for ventilation. Comfort backpack straps with hydration or headphone routing, a reflective hit and detachable sternum strap. Front panel unzips to expand volume for carting extra bulk. Do it in a downpour; will keep the contents of your bag dry for several hours in the rain - Internal drop liner with waterproof seam tape construction. External compression straps for cinching or expanding. Reflective hits. Vista loop for attaching blinky bike lights. Water resistant, PU coated YKK zippers.