HumanTechnik InfraLight A-4010-0 Mode D'emploi page 15

7
If the sound quality of the receiver becomes noisy and distorted you
should replace the battery pack with a charged one or charge the
receiver, including battery, in its cradle.
Warning: do not force the battery pack into the charger or
receiver. It fits easily when in the correct orientation.
Maintenance of the headset receiver
8
The ear pieces have to be cleaned or exchanged if dirty.
Please use for this the hygienic-set (order no. A-4982-0)
which is available as a special accessory.
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