Contain only pressurised CO₂ gas and leave no residue. This type of extinguisher is suitable for use on fires involving burning liquids (Class B fires), but is also an excellent solution for quenching fires involving computer equipment and other electrical appliances , as it does not cause damage to the electrical items and does not cause the system to short circuit. It is important to remember that when using CO₂ extinguishers there is a possibility that once the gas has floated away the fire may reignite if the source of the fire is not removed (e.g. switching off the power supply). Please be aware that CO₂ extinguishers that are not fitted with double-lined swivel horns which may cause your fingers to freeze to the horn during the deployment of the CO₂ gas.