The X-Series earmuffs are 3M's latest advancement in hearing conservation. New technologies in comfort, design and protection all come together in this groundbreaking earmuff line. The X4A utilizes a newly designed spacer, specially formulated foam liners and innovative ear cushions to help improve attenuation. This lightweight, lower-profile earmuff helps with compatibility with other personal protective equipment and is designed for protection against moderate-to-high level industrial noise and other loud sounds. It features an electrically insulated wire headband, often referred to as "dielectric". The wire headband offers consistent pressure over prolonged wearing periods. Earcup pivot points tilt for optimum comfort and efficiency. Noise Reduction Rating (NRR)b 27 dB. CSA Class AL. NOTE: The X-Series (over-the-head) headband version is electrically insulated - sometimes referred to as "dielectric". The metal components of the headband have been covered by non-conductive material for use in a low voltage electrical hazard (less than 440 V ac). As there are no applicable standards for testing ear muffs against electrical insulating properties, the product has been evaluated at an external laboratory against a modified test method based on EN397:1995. During assessment, the leakage current did not exceed 1.2mA when the external surface of the product made contact with an electrical source. The user must determine the overall suitability of this product for the intended application taking into account any hazards other than noise for which this product is tested. The NRR may overestimate the hearing protection provided during typical use. 3M recommends reducing the NRR by 50% for estimating the amount of noise reduction provided.