In 2019 it has become very difficult to find Prestige "Ready to
Serve" indicators that form the safety valve for older Prestige
pressure cookers - High Dome and other aluminium pressure cookers.
The rubber and metal types are no longer being made, but there is
A new all metal safety valve is available and it fits straight in
to the same diameter hole in the pressure cooker.
The new valves do the same job for safety, but they
don't replicate the function of showing when the cooker has
depressurised at the end of cooking. For this you have to follow
the original Prestige instructions (when these cookers were first
made the rubber plug was just a safety value - the pop up "Ready
to Serve" valve was a later development). To check for
depressurisation you have to tip the weight slightly to the side
and check if steam escapes - once you're certain there's no
hissing steam the cooker is safe to open.