Explain sound quality:High-definition sound quality and intelligent noise reduction health:Not for wearing in the ears, with lanyard Number of channels:9999 channels, 9999 channels available Multiple giving lectures at the same time. Transmission distance:150m transmission, The transmission distance can reach 150 meters without interruption. Specification:B: Receiver The chest-mounted receiver has a battery life of up to 96 hours non-stop. (The product printed words depending on the batch, but this does not affect use) Color:As Shown Material:ABS Package Contents: 1 * Simultaneous System Audio Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.