This popular, comfortable two-color earplug comes in a bulk pack of 500 pair per box. The box is designed to be used as a refill for the Leight Source 500 earplug dispenser. Users have commented that they are excellent for people with smaller ear canals, and also that they work well for work and for sleeping. It's not recommended to do both at the same time. Box contains 500 pair, or 1000 total ear plugs. These uncorded plugs are rated NRR 32 (or Noise Reduction Rating of 32). NRR is calculated by unprotected ear dB levels minus protected ear decibel levels minus 3 dB. The higher the NRR rating, the better the protection.