1.changeable boom microphone 2.For our B50, B51, C50, C51 series H/D headset 3.Flexible microphone with replaceable windshield Electret boom microphone to suit Heavy Duty Headsetfor our B50, B51, C50, C51 series H/D headsetFlexible microphone with replaceable windshield foam Electret boom microphone to suit Heavy Duty Headset.