A replacement heat exchanger plate, in case you need a new one.
The 9Barista machine comes with one of these as standard. The plate is needed if you want to use 9Barista on a domestic gas cooker, or an induction cooker.
The plate is made from three layers (stainless steel – aluminium – stainless steel), which are diffusion bonded together. It enhances heat transfer from the heat source to the machine.