Harbor Backpack (MD) Dark Brown. Our best-selling backpack just got smaller! The Harbor Backpack was specially designed for urban bike riders. Made using a TPU membrane and nylon fabric, welded seams, and locking waterproof zippers, this bag is 100% waterproof in both fabric and construction. The padded shoulder straps, back support technology and waist stabilizer straps come in handy whether you are riding for 5 minutes or 50 minutes.