9 CFR § 312.5 - Official seals for transportation of products.
The official mark for use in sealing railroad cars or other means of conveyance as prescribed in part 325 of this subchapter shall be the inscription and a serial number as hereinafter shown 2 and any seal approved by the Administrator for applying such mark shall be an official device for purposes of the Act. This seal shall be attached to the means of conveyance only by a Program employee and he shall also affix thereto a “Warning Tag” (Form MP-408-3).
2 The number “2135202” is given as an example only. The serial number of the specific seal will be shown in lieu thereof.