Designed specifically for arc blast hearing protection, new E-A-R ARC Plug earplugs feature patented Hear-Throughâ„¢ filter technology, which allows the wearer to hear sounds around them clearly (conversation, traffic, etc.), while being protected from an impulse noise (arc blast). A second side (red) of the ARC Plug protects against high-level noise (NRR 22dB). Aearo Co./E-A-R, Indianapolis, IN.