Item Type: Wireless Lavalier Microphone Material: ABS Model: K9 Frequency Range: Bluetooth Frequency Response Range: 20-200KHz Microphone Built-in Lithium Battery Capacity: 2 x 60mAh (Built-in) Transmission Distance: 20m / 66ft Transmission Delay: 30MS Sensitivity: -42dB Microphone: Silicon Microphone SNR: 64dBm Usage Time: About 4 hours Anti-Interference & Stable: Adaptive frequency hopping ensures strong anti-interference, a stable signal, and long-distance transmission. Plug & Play: Automatic pairing for easy setup. Supports slow or fast phone charging while recording. High Sensitivity: Built-in 360-degree omnidirectional HD high-sensitivity microphone, also supports ECM, MEMS, and analog microphones. Broad Compatibility: Compatible with mobile phones, computers, and tablets. Rechargeable Battery: The Type-C wireless lavalier microphone audio unit has a built-in 60mAh rechargeable button battery for 6 to 10 hours of battery life. Includes: 2 x Receivers, 1 x Transmitter, 1 x Manual, 1 x Charging Cable