PHMSA is issuing this safety advisory notice to inform the public, industrial gas stakeholders, and relevant government officials of the risks associated with requalifying, filling, and transporting cylinders bearing the DOT specification markings "DOT 4E" or "DOT 4BA" that were produced by a company located in Thailand by the name of Metal Mate. Metal Mate does not have an approval from PHMSA to manufacture cylinders to DOT specifications; therefore, cylinders marked with the Metal Mate name are not DOT specification cylinders.