It is a type of fire extinguisher that uses carbon dioxide to suppress fires by displacing oxygen and cooling the fuel. The image shows a 2kg CO2 fire extinguisher with instructions on how to use it:
1. USE UPRIGHT PULL OUT PH (likely referring to the safety pin)
2. AIM NOZZLE AT BASE OF FIRE FROM APPROX 2 METRE
3. SQUEEZE HANDLE TO OPERATE RELEASE HANDLE TO INTERRUPT