Features: The microphone consumes 100mA and is powered by 2x1.5V battery, it can be continuous used for 8 hours. This product adds several new domestic unique technologies based on the original microphone technology, which makes the system have ultra-high sensitivity, strong anti-interference ability and excellent stability. The original technology includes high-efficiency low-loss RF emission technology and SMT production process in the United States, and uses a locking frequency of better than 10ppm quartz crystal, dynamic audio compression, expansion circuit, and image frequency. The frequency is fixed, it can be used at boot, very convenient. Suppression circuit, shock elimination circuit during switch, adopts anti-return circuit slow-change output control technology, computer EDA, analog online auxiliary design, etc. Four channel volume is independently adjustable, providing 1+4 audio output, and it can be simultaneously used by stacking 5 different frequency points. Specification: Material: ABS Size: Approx. 42x20x4.2cm/16.54x7.87x1.65inch Standard: US, UK, EU(optional) Name: Wireless 4 Channels handheld microphone Model: SM-58G Battery: 2xAA (not included) IF-FRE: First 110MHz, Second 10.7MHz Wireless Interface: BNC/50ohms Sensitivity: 12dBμV (80DbS/N) Sensitivity Adjustment Range: 12-32 dBμV Stray rejection: ＞75dB Max output level: +10dBV Transmitter Parameter: Wireless Program: Built-in spiral antenna for handheld microphone Wireless Pattern: Output Power: High power High power 30mW; low power Low power 3mW Stray rejection: -60dB Duration Time: ＞8 hours(30mW), ＞12 hours(3mW) Use distance: Open environment: Approx. 50-80m/164.04-262.47ft, Complex environment: Approx. 30-40m/98.43-131.23ft Package List: 1 x Transmitter 4 x Microphone 2 x Antenna 1 x Instructions 1 x Audio Cable 1 x Power Adapter 4 x Fixed Ring 2 x Holder