Section 211.211 - Compliance with labeling requirement(a) All hearing protective devices manufactured after the effective date of this regulation, and meeting the applicability requirements of § 211.201 , must be labeled according to this subpart, and must comply with the Labeled Values of mean attenuation.(b) A manufacturer must take into account both product variability and test-to-test variability when labeling his devices in order to meet the requirements of paragraph (a) of this section. A specific category is considered when the attenuation value at the tested one-third octave band is equal to or greater than the Labeled Value, or mean attenuation value, stated in the supporting information required by § 211.204-4 , for that tested frequency. The attenuation value must be determined according to the test procedures of § 211.206 . The Noise Reduction Rating for the label must be calculated using the Labeled Values of mean attenuation that will be included in the supporting information required by § 211.204-4 .47 FR 57717, Dec. 28, 1982