The Hong Kong Perfin Study Circle
has identified 66 Agencies that used perfins to prevent theft of stamps. Of these, six are known to have used perfins on 1935 Silver Jubilee stamps. One other Hong Kong Company, Banque de l'Indo-Chine (BI), may have used perfins.
The companies listed in blue are those where perfin copies are available for viewing. Click on the company to view the stamp.