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 Mic SNR: 64dBm Use Time: About 4 Hours 1、[Anti Interference and Stable] Wireless lavalier microphone adaptive frequency hopping, strong anti interference, stable signal, long distance.  2、[Function] Wireless lavalier mic auto pair, plug and play, supports slow charging or fast charging of phone (while recording and charging).  3、[High Sensitivity] Built in 360 degree omnidirectional HD high sensitivity microphone, also supports for ECM, for MEMS, for analog mic.  4、[Good Compatibility] Lavalier lapel microphone has good compatibility and supports mobile phones, computers, and tablets at the same time.  5、[Rechargeable Battery] Type C wireless lavalier mic sounder built in 60mAh rechargeable button battery for 6 to10 hours of battery life.