Hi there, @Statsminister! At this time, the Dome Siren is only available for the North American region. While Ring Alarm is available in several regions, our devices will vary by region for many reasons including regulations and compliance differences. For this reason an Alarm system from the US is not intended to be used in the EU, for instance. This is also true for accessories such as the Dome Siren. Shipping information and availability can be confirmed for most Ring devices at Ring.com.
As an alternative, there is the option to use Linked Devices to link your Ring Cameras that have a siren feature to also sound when your Base Station siren is sounding. I hope this helps! 