Ideal Standard / Armitage Shanks 1 1/2" Pneumatic Dual Flush Valve SV93467
With the SV93467 flush valve's design you need not worry about removing the entire cistern to service the valve in future, just simply twist the valve in an anticlockwise direction and the whole top mechanism just lifts right out.
All that is needed then is to twist clip the new valve into place (or the same valve if you're just replacing the base seal), connect the push button or flush plate and you're ready to go.
Thread Diameter: 1 1/2"
Flush Type: Dual Flush
Manufacturer: Ideal Standard