Just need a few? Pay $6.95 per Tube and CO2 Cartridge. Our tubes are quality 700c 23-25 Butyl Road Bike tubes with 60 mm threaded Presta valves. Our threaded CO2 Catridges are designed especially for inflating road bike tubes and contain 16 grams of CO2. Need more? Buy 6 or 12 for Free Shipping. Buy 12 to get Free Shipping and 2 extra Cartridges (for your friend who never has one).