Hdlsina Tactical Shooting headset with U94 PTT 2pin and ARC Rail Adapter Noise Reduction & Sound Pickup Ear Protection Conversion of two application modes, 1.The ACR rail adapter is compatible with the full range tactical FAST helmets, ACH helmets, MICH helmets with OPS Core ARC rail on the sides, 2.Fits for all 19-21mm rail,can be effectively fixed and not easy to fall. 3.Very valuable combination:Equipped with The Multifunction ARC rail adapter,With a full 360-degree rotative design, the ear cups can be rotated to fold to the side or back of thetactical helmet. A Good Helper to Protect Your Hearing A Good Helper to Protect Your Hearing 1. Runs on 2 AAA Batteries (not included) with waterproof battery cap. 2. This Version not Only has Communication Function, but also this headset has electronic active noise reduction and sound pickup technology,( sound collection function / soundproof function / hearing protection function), 3. When the ambient noise exceeds 80 decibels,this series of tactical headphones has a very obvious noise reduction effect, which is a good protection of our hearing! THE RATE OF HEARING IMPAIRMENT CAUSED BY NOISE： 80 DECIBEL：Upper limit of human ear comfort 90 DECIBEL：Many countries defined as occupational exposure limits 95 DECIBEL：Noisy bar, chainsaws slicing through wood 100 DECIBEL：Pneumatic drill, compression hammer strike sound 110 DECIBEL：Damage to the auditory system 120 DECIBEL：Propeller planes, rock concerts 125 DECIBEL：high pressure air rifle 130 DECIBEL：Jet plane takes off，pistol 140 DECIBEL：The European Union defines the threshold for total hearing loss ARC Rail Adapter Function Flapping Up or Down The spring and Rotation of brackett mounting design,the bracket arm can be flapping up or down,When not in use, Flip to the back of the helmet It can be folded behind the helmet for storage with management cable latches The tactical helmet connection arm comes with a buckle for the management wire, The headphone cable can be stored and organized to prevent the messy headphone cable Come With Two Adapters Compatible with both OPS Core and Team Wendy M-LOK Rails How To Install The Microphone 1.According to the usage habit, select the left or right microphone fixed socket, insert 2. Plug the microphone signal power cord into the corresponding port 3. Screw the screw into the retaining socket of the microphone,This step holds thmicrophone in place and prevents it from rotating,This step is important for the stability of the microphone,Buyers complain,The mouth mic spins around loosely.The important reason is that the screws are not fixed properly With U94 type headset PTT With U94 type headset PTT,Fit standard version plug Adapter Mobile 2 Pin 7.0mm Plug , fits for Kenwood 2 pin radio.theTactical headset has the NATO standard 7MM plug, It should work work perfectly. Fits for Kenwood 2 pin radio theTactical headset has the NATO standard 7MM plug, It should work work perfectly. Standard U94 type headphone connector with Serrated metal clip clip, the clip has a good bite force for attaching to clothes or MOLLE webbing strap tightly.