NRR, or Noise Reduction Rating is a rating system set up by the Environmental Protection Agency (EPA) as a guideline that indicates the amount of potential protection a hearing protection device will give in a noisy environment. All Howard Leight hearing protection devices are tested under the Real Ear Method as directed by the American National Standards Institute (ANSI) in accordance with test procedures established by the Acoustical Society of America. All testing is performed in a controlled environment. Subsequently, posted NRR ratings are a qualified example of how the individual products compare to other similar hearing protection products in an uncontrolled noise environment. Test results do not evaluate the product reusability, comfort, adaptability or quality. In the final analysis the user must make this determination.

SNR, or Single Number Rating, is a rating system set up by the European Union (EU). Tests are conducted by independent testing laboratories with no direct participation by manufacturers. The independent testing laboratories meet all of the regulatory requirements as set out by the EU. The test results serve as a guideline to indicate the amount of potential protection a hearing protection device will give in a noisy environment. All Howard Leight hearing protection devices are tested according to the requirements established under EN 352.2 1993 (ear plugs) and EN 352.1 1993 (earmuffs). All tests are performed at independent testing laboratories located at either B.I.A., Germany, or by Inspec Laboratories LTD, England at the University of Salford, Department of Acoustics.

The CE mark is a symbol of conformity on industrial safety products that have been approved for sale in the European Union (EU). CE conformity indicates that the safety product and systems within the manufacturers company satisfactorily meet, or exceed, the established requirements of quality assurance, user information, and on-going testing. Effective July 1, 1995, all safety products sold into the EU must be tested, approved, and carry the CE mark.