https://www.scmsinc.com/sound-devices-xl-b14500-lithium-ion-rechargeable-battery.html
Sound Devices XL-B14500 Lithium-Ion Rechargeable Battery
Rechargeable Li-ion batteries provide over 10 hours runtime, hot-swappable power, and flexible use for Astral TX transmitters in pro audio setups.
sound deviceslithium ionxlrechargeablebattery