Del. Code tit. 6 § 3704
Any person, or any agent or employee thereof, who sells a secondhand watch shall deliver to the vendee a written invoice setting forth the name and address of the vendor, the name and address of the vendee, the date of the sale, the name of the watch or its maker, and the serial numbers, if any, or other distinguishing numbers or identification marks on its case and movement. In the event the serial numbers or other distinguishing numbers or identification marks have been erased, defaced, removed, altered or covered, this shall be set forth in the invoice. A duplicate of the invoice shall be kept on file by the vendor of the secondhand watch for at least one year from the date of the sale thereof and shall be open to inspection during all business hours by any member of the police department of the City of Wilmington or other peace officer of the State.
6 Del. C. § 3704