letter agreement

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Electronic                                         1077 Business Center Circle

Sensor                                             Newbury Park, California 91320

Technology                                         Tel. (805) 480-1994

                                                   FAX (805) 480-1984

October 3, 2005

James Frey

1305 Ballantre Court

McClean, VA 22101

Dear Jim:

          On February 21, 2005, you entered into a letter agreement with

Electronic Sensor Technology, Inc., a Nevada Corporation (the "Company"),

pursuant to which the Company appointed you to the position of Chairman of the

Board of Directors for the Company for a two year term (the "Letter Agreement").

To induce you to serve as Chairman of the Board of Directors of the Company, the

Company made certain assurances to you regarding equity compensation

("Assurances") and purported to execute on those assurances by means of the

Letter Agreement. Following the execution and delivery of the Letter Agreement,

each of you and the Company