Listen Only Headsets with 3.5 mm Mono Audio Cable are an ideal companion for 'listen only' situations, like monitoring a scanner or race receiver, as they have a 3.5mm scanner/music port along with a 3.5mm coiled mono cable. The headsets, which feature a volume control knob, can establish a direct connection with your scanner or Nitro Bee race receiver. You can listen to race traffic without distractions from surrounding noise around the track and stands. These headsets, available in Over-the-Head and Behind-the Head styles, can block up to 24 dB of surrounding noise. Power requirements are minimal with no batteries or charging required. The package includes a H20 Over the Head or H40 Behind-the-Head Headset and an expandable mono coil cord.