As per new regs 1st of April all gas instaltions using composite pipework must have excess flow valves fitted at the meter assembly - This unit tirggers at 240mj/hr others models available for bigger instatalions.

Must be fitted vertically and arrow down.

more size units here

Excess flow valve GS10K (gasstop.com.au)

Excess Flow Valve GS16K (gasstop.com.au)