OTTO NoizeBarrier Micro Earplug. Up to 40 dB of impulse noise protection. Up to 15 dB adaptive noise protection. NRR: 28 dB(Foam Tips); 23 dB (3-Flange Tips). Natural hearing for safe sounds. Accu-Technology high-definition sound quality. One-button touch pad, 2-mode operation. Rechargeable with up to 16 hours of continuous use. Charging station: up to 20 earplug charge cycles. Earpiece and case IP67 water resistant.