The H41 headset provides two-way radio communication when connected to your radio and can be used in applications including auto racing, industrial and heavy equipment operation, recreational off-roading and more. The 5-pin port on this headset allows you to connect virtually any handheld radio on the market using a radio specific jumper cable. Features: Dynamic noise cancellation microphone 3.5mm input jack for use with MP3 players and racing scanners Clear Hear speakers for unsurpassed audio performance. 24 decibels NRR (Noise Reduction Rating) hearing protection Easy to use volume control knob