Shure BLX14/SM31 H9 Wireless Fitness Headset SM31 Microphone System 512-542 MHz
Shure BLX14/SM31 H9 SM31 Wireless System (H9: 512 to 542 MHz). Legendary sound and performance, right out of the box. Shure BLX14/SM31-H10 Wireless Fitness Headset Microphone System SM31 Mic. Legendary Shure precision engineering for durability and performance.