Helicopter Headset with Flexible Boom MicFEATURES Active Noise Straight Cord Reduction OVER-THE-HEAD STYLE Noise Reduction Ratings (NRR):29dB HOW TO PUT THE BATTERY ♦ Helicopter use U174/U plug. ♦ ANR Active noise reduction headset with electret microphone. ♦ Active Noise Reduction Ratings(NRR):29dB. ♦ Passive Noise Reduction Ratings(NRR):23dB. ♦ Small AA battery box with belt clip.(Battery not include) ♦ Strong flexible boom for perfect microphone placement. ♦ Low profile volume control knob with detent settings. ♦ Fully adjustable spring steel headband. ♦ Colors: black,blue,yellow,green .gray,pink,red.