Arundel Seat Bag - Dual - BlackThe Dual is small enough to nestle under a seat without scraping against your thigh, yet its big enough to hold two 700C tubes and two CO2 cartridges, plus an inflator. So, why two spare tubes? Because you never know whats up the road, and its nice to know that youre prepared. That extra tube will make the rest of your ride that much more enjoyable knowing that you wont have to use your cell phone if another flat occurs.