1、Support 2 people, 3 people, 4 people connected to full‑duplex intercom (up to 4 people can talk at the same time). The maximum intercom distance is 2100 meters/6889.8ft. (the distance between the first and fourth people can reach 2100 meters, and any two people in the middle are 700 meters) 2、Bluetooth connect to mobile phone, can be connected to two mobile phones at the same time, the distance is 10m/32.8ft. It can realize automatic answer, manual answer/hang up/refuse to receive/re‑dial/voice dialing and other functions. 3、Connect the mobile phone to play music, you can control the previous/next music, increase/decrease the volume. 4、During the intercom, you can manually switch to the mobile phone, automatically switch to answer the call when the mobile phone calls, and automatically switch back to the intercom when you hang up the call. (Can be switched in the music, intercom and phone functions) 5、Support single microphone software noise cancellation and suppression functions to ensure clear voice quality. It can be played in GPS audio source or stereo media and switched with Bluetooth intercom voice. for DSP noise reduction function. 6、IP67 waterproof. Notified electric quantity (3 levels: full electric quantity, half electric quantity, low electric quantity). Built‑in FM radio function (button to adjust volume and radio). Low Power Notification (once every 5 minutes) 7、Can be paired with other types of Bluetooth headset (helmet Bluetooth intercom, helmet Bluetooth headset, ordinary Bluetooth headset) 8、Connect the ordinary walkie‑talkie through the intercom cable (access to the USB interface), and press the PTT button on the intercom cable. This function can be realized in T9S‑V3 shutdown/startup state. And connected to the ordinary intercom, there are other voices come in. For example, cell phone calls, music, intercom, FM radio, sound signals will be mixed and listened to at the same time. Item Type: Bluetooth Intercom Material: ABS Color: As Pictures Shown Weight: Approx. 400g/14.1ozBluetooth Version:  V3.0+EDR Support: A2DP AVRCP HS/HF Working Time: About 15h Standby Time: About 350h Charging Time: About 3h Battery: Built-in Lithium Battery 3.7V, 800mA 1 x Intercom 1 x Earphone Cable 1 x Hard Microphone 1 x Soft Microphone 1 x Screw Clamp 1 x Gasket 2 x Screw 1 x Wrench 1 x Hook and Loop Fasteners Clip 1 x USB Cable (for Android Interface) 4 x Hook and Loop Fasteners 1 x Manual