31 CFR § 601.4 - Distinctive counterfeit deterrents.

The distinctive counterfeit deterrents that may be used in the denominations of United States Federal Reserve notes as prescribed by the Secretary of the Treasury are:

(a) Security threads containing graphics consisting of the designation “USA” and the denomination of the currency note, expressed in alphabetic or numeric characters.

(b) Optically variable inks with material characteristics.

(c) Non-visual characteristic inks with material characteristics.

(d) Optically variable thread (three-dimensional (3–D) security ribbon and micro-optic stripe) visible in front or back of the currency note.

(e) Non-visual characteristic features with material characteristics.