When an external remote thermostat housing is fitted to an MG/Rover K Series installation, the existing thermostat is removed. However, the gasket has a slot for the thermostat so needs something in its place to ensure a good seal. In the past it has been normal practise for the old termostat to be refitted with the centre cut off. Some even offer exactly that to buy. We've laser cut these stainless inserts that have an aperture more than double the area of the old solution, therefore improving coolant flow which is vital in these engines as they are not very tolerant of fluctuations.
Does not include the gasket, fits in your existing one.