This is the new Avent Comfort Natural Electric Breast Pump.
Check the diagram to ensure it matches your pump, because Avent also have an older model called the Avent Isis which has different parts – and the pieces are not interchangeable. (see spare parts for the Avent Isis electric pump)
You can shop here to buy all the pieces suitable for this version: Avent Comfort Electric Pump Parts
Avent Comfort Electric Pump Parts NZ Australia