Description: Bluetooth 3.0 professional chip,1200m Bluetooth actual intercom distance, 3 people switch intercom in pairs HD binaural headphones, stereo music, Professional waterproof, windproof, high power, support A2DP EDR Answer calls automatically,FM radio function,650 mAh lithium battery,Standby for 300 hours Work more than 12 hours 10. Intercom with similar products of other brands Connect 3 Bluetooth devices at the same time Specification: Bluetooth power: class one Transmitting power: 21dbm Receiving sensitivity: -83dbm Support Bluetooth protocol: A2DP, AVRCP, HSP / HFP, AGHSP, PRIVATE INTERCOM Battery capacity: 650mah Talk time: 12 hours Charging time: 2.5 hours Battery type: lithium polymer battery Standby time: 350 hours Maximum communication distance: 1200 meters (varies according to the actual test environment) Maximum number of people: 3 people switch intercom Radio frequency band: Japan: 76M ~ 91M General: 87M ~ 108M Host weight: 47g Host size: 85 * 42 * 23 mm Certification: FCC, CE, TELEC Audio: Noise Reduction Power Volume Adjuster Built-in stereo decoder Maximum sampling 48khz Antenna: built-in Speaker impedance: 32 ohms Frequency response: 20HZ-16KHZ Size: 85x42x23mm Package Includes: 1 x Helmet Intercom. 1 x Bluetooth Headset. 1 x USB cable. 1 x Clip Mounting Bracket. 1 x User manual. Note: Charge plugs are no longer provided