39 U.S. Code § 3002a. Nonmailability of locksmithing devices

(a) Any locksmithing device is nonmailable mail, shall not be carried or delivered by mail, and shall be disposed of as the Postal Service directs, unless such device is mailed to—
(1)
a lock manufacturer or distributor;
(2)
a bona fide locksmith;
(3)
a bona fide repossessor; or
(4)
a motor vehicle manufacturer or dealer.
(b) For the purpose of this section, “locksmithing device” means—
(1)
a device or tool (other than a key) designed to manipulate the tumblers in a lock into the unlocked position through the keyway of such lock;
(2)
a device or tool (other than a key or a device or tool under paragraph (1)) designed for the unauthorized opening or bypassing of a lock or similar security device; and
(3)
a device or tool designed for making an impression of a key or similar security device to duplicate such key or device.