This Pressure Relief cap is rated to 1.1 BAR or 110Kpa
And fits GU ZD30, TD42TI and RD28 Models
Where the Pressure cap is fitted to the Over flow bottle, and the radiator has a blanking cap.
(This will aslo fit a standard radiator if you wish to change your pressure rating)

These are an item that are common to fail,
if you are chasing a pressurising problem with your cooling system, this is a good place to start.

Note: The blanking cap is sold seperately.