The new XL-9V 9 volt battery pack from David Clark is easier to operate, wear and store. It is 50% smaller and 50% lighter than previous battery packs.
The model XL-9V battery pack uses a 9 volt alkaline battery (40862G-01) to provide power to the headset ENC system. The XL-9V features an Auto Shut Off function to save the battery if the power switch is left on when the headset is not in use. The Auto Shut Off feature operates by sensing loss of microphone DC bias voltage when the headset is unplugged or aircraft audio system is shut off.
I had a headset that needed this to work in a GA aircraft. It worked perfectly and made my headset more than a paperweight.
This battery pack is for the David Clark H10-13X Fixed wing headset part number 11-03819.