Case: Its 750mAh internal battery can recharge the transmitters twice for a total battery life of 40 hours. The transmitter features a dual-interference design with a metallic mesh that protects against dust and 2.4 GHz, infrared, and RFI interference. The transmitters feature a 90mAh internal battery with a 10-hour battery life. Once depleted, recharge the transmitters in the included charging case or via USB-C ports. Environmental noise cancellation minimizes frequency interference for improved vocal clarity. The LARK M2 captures 24-bit 48 kHz audio with a 70 dB signal-to-noise ratio and 115 dB SPL. Connect your LARK M2 system to the LarkSound App to adjust parameters like volume and noise cancellation, update firmware, or check real-time audio statusall from your iOS or Android compatible smartphone.