SECURITY DEVICES INTERNATIONAL, INC.

                              464 Old Orchard Grove
                                Toronto, Ontario
                                 Canada M5M 2G4

                               September 18, 2007

Jay Mumford
Tara Harkins
Securities and Exchange Commission
Division of Corporation Finance
100 F Street, NE
Washington, DC 20549

      Re:   Security Devices International, Inc.
            Form SB-2
            File No. 333-143301


     Security  Devices  International,  Inc. (the  "Company")  requests that the
effective date of the above captioned  Registration  Statement be accelerated to
Thursday, September 20, 2007, 10:00 a.m. Eastern time, or as soon as practicable
thereafter.

     The Company understands that:

     o    should the  Commission  or the staff,  acting  pursuant  to  delegated
          authority,  declare the filing  effective,  it does not  foreclose the
          Commission from taking any action with respect to the filing;

     o    the  action  of  the  Commission  or the  staff,  acting  pursuant  to
          delegated  authority,  in  declaring  the filing  effective,  does not
          relieve the Company from its full  responsibility for the adequacy and
          accuracy of the disclosure in the filing; and

     o    the Company  may not assert this action as defense in any  proceedings
          initiated by the Commission or any person under the federal securities
          laws of the United States.

                                Very Truly Yours,



                                /s/ Sheldon Kales
                                -------------------------------------
                                Sheldon Kales, President