Ann: FY2016 results-ACG.AX, page-65

The reason they would use SphygmoCor over the others would be that SphygmoCor provides normals and shows where a patient fits in those normals. The normals are based on thousands of patients and cannot be reproduced without a major costly clinical study by its competitors.

Given what we have been discussing regarding lack of specific guidelines, the normals is the reason why a doctor would choose SphygmoCor over its competitors (and the fact that it has been most widely used/published and accurate of the devices in this space). Note, only a 1-2 competitors have US FDA approval which is where the $$ are.