The Noise Reduction Rating (NRR) is placed on the packaging to indicate the amount of attenuation obtained from a particular device. Since field or “real world” values have been found to be significantly less than that of the laboratory, the NRR of the hearing protection device should be de-rated by 50% (cut in half). This value should be subtracted from the worker’s noise exposure findings to determine the number of hours that can be worked in hazardous levels of noise while wearing this device. Contact us for quote and advice on which type to purchase.