The Topeak Ninja Master Roadbox is the perfect add-on for your Topeak Ninja bottle cage! It has been designed to hold a 700 x 25c tube, meaning you'll no longer get stuck by the side of the road when you inevitably get a flat. Thanks to the clever design, all it takes is one twist, to attach or detach the Roadbox. You shouldn't restrict the use of the Ninja Master Roadbox - it's the perfect size to size to carry a multi-tool, keys or your wallet. The added bonus of a water-resistant lining means that you can even keep paper-based items with you if you so desire.