If your machine is leaking from the area around the coffee filter this is the part you need.
Ensure that you are purchasing the correct part as there are three versions of the Breville gasket. Here is a link to the 50mm version and the 54mm version
Please check your machine series number before purchasing
58mm Steam Ring fits:
Dual Boiler™ BES900XL and BES920XL
Oracle™ BES980XL