Multi-Usage: Expansion Activities, Tactical Games, Film and Television Props, Team Activities, Cosplay and Other Outdoor Sports. Use Headset by Hang On the Helmet // Detachable microphone Free to Install // fits 19~21mm helmet side rail No need to install battery, battery Slot and Buttons is For Decoration (Useless). New Design Ear Cup Provide Clear Voice and Comfortable Support. Please Note: This Version Only has Communication Function, No Noise Reduction Function // This Product Cannot be Used Alone and Needs To be Used with PTT. This item is eligible for complimentary air shipping.