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