(a) Except as permitted in sections 4(b)(1) and 4(b)(2) of the Act, as amended, no fiber present in the amount of less than 5 percent of the total fiber weight shall be designated by its generic name or fiber trademark in disclosing the constituent fibers in required information, but shall be designated as “other fiber.” When more than one of such fibers are present in a product, they shall be designated in the aggregate as “other fibers.” Provided, however, that nothing in this section shall be construed as prohibiting the disclosure of any fiber present in a textile fiber product which has a clearly established and definite functional significance when present in the amount contained in such product, as for example:

(b) In making such disclosure, all of the provisions of the Act and regulations in this part setting forth the manner and form of disclosure of fiber content information, including the provisions of §§ 303.17 and 303.41 of this part relating to the use of generic names and fiber trademarks, shall be applicable.