Sennheiser MM 400 Instructions for Use - Page 9

Putting the MM 400 into operation Putting the MM 400 into operation Before using the MM 400 for the first time, remove the protection strip from the battery pack. Charging the battery pack ̈ Before using the battery pack for the first time, charge it for at least 3h 3 hours. When charging the battery pack, the LED ¾ on the battery pack lights up red. When the battery pack is fully charged, the LED ¾ on the battery pack lights up green. ¾ 1 When the battery pack is almost flat, the LED ቢ on the headset flashes 3s red. You hear a short, negative acknowledgement tone. The operating time of the battery pack depends on the device settings, the listening situation and the audio sources used. Type of use Bluetooth technology Operating time 10 hours Remove the battery pack if the headset will not be used for extended periods of time. You can also charge the battery pack while using the headset. 8