There are also different sizes of fire extinguishers. Bigger fire extinguishers can be used for a longer time. Hand-held fire extinguishers vary between 0.5 and 14 kg. A 2 kg extinguisher works for about two to four seconds, the 12 kg model for about eighteen seconds. There are also bigger fire extinguishers, mounted on a cart or a vehicle. These are used to fight fires at airports, for example.