Amazon.com: Shure BLX14/SM31 UHF Wireless Microphone System - Perfect for Fitness, Aerobics - 14-Hour Battery Life, 300 ft Range | Includes SM31FH Fitness Headset Mic, Single Channel Receiver | H9 Band : Musical Instruments
Shure RK379 Replacement Accessory Kit for SM31FH Headset RK379
Shure SM31FH-TQG SM31FH Fitness Headset Condenser Microphone – Easy Music Center