Instead of exhaustingly pumping stroke by stroke, CO2 pumps use a disposable cartridge and enable you to reach the desired tyre pressure quickly. They're small and light and therefore ideal as a quick solution for repairs on the go. CO2 cartridges usually screw-in with a similar principle to a camping cooker. Many CO2 pumps are consequently little more than a valve adapter and use the cartridge as the body. The neoprene often used over the cartridge body is therefore not a marketing gimmick; the aluminium gets very cold! If you want both the convenience of a CO2 pump and the reliability of a mechanical handpump, look for a hybrid model that offers both functions.