The Zipp 16g CO2 Cartridges | 20-Count Box...get what you need all at-once. Buy in bulk, save money and have plenty of spares. They're the perfect companion when you puncture a bike tire. Easily inflates 700c and 650c bicycle tires. Plus they're lightweight, compact and a breeze to use with a compatible inflator or bike pump. Get the Zipp 16g CO2 Cartridges | 20-Count Box today and ride with peace-of-mind.