Free Shipping. Lifetime Warranty. The Clark Commuter Backpack is Timbuk2's ultra-tough weatherproof expandable roll top that has room for everything you need and a little more. It features multiple exterior pockets for separating delicate devices from heavy U-locks and its rolltop closure keeps the weather out. With nearly impenetrable PVC construction, grommeted drain holes, and a removable rainfly, Clark will protect your gear from flash floods and bad guys.