19 C.F.R. § 101.7 – Customs seal.

(a) Design. According to the design furnished by the Department of the Treasury, the Customs seal of the United States shall consist of the seal of the Department of the Treasury surrounded by an outer circle in which appear the words “Treasury” at the top and “U.S. Customs Service” at the bottom.
(b) Use of the Customs seal. The Customs seal currently in official use, including the dies, rolls, plates, and like devices now in the possession of the Bureau of Engraving and Printing, shall continue to be equally effective as the official seal of the United States Customs Service and shall continue to be so used by each Customs officer and employee having possession of the seal until that particular device requires replacing and is replaced. Use of the United States Customs seal shall be restricted in the following manner:
1. (1) The Customs seal of the United States shall be impressed upon all official documents requiring the impress of a seal. It shall be impressed upon all marine documents and landing certificates, certificates of weight, gauge, or measure, and similar classes of documents for outside interests.
2. (2) The impress of the seal is not necessary on documents passing within the Customs Service nor shall the seal be used in the manner of a notary seal to indicate authority to administer oaths.