The Yamaha RM-WBT is a rechargeable lithium-ion battery for use with the ADECIA RM series of wireless conferencing microphones. The battery is available as a replacement if the original is worn out or lost or as a backup battery to ensure you don't run out of power during an important conference. The battery is compatible with the RM-WOM, RM-WDR, RM-WGL, and RM-WGS microphones.