Replacing the battery is a little tricky. A small screwdriver or similar tool is needed to release and re-close the battery compartment clip.
The battery compartment clip sometimes breaks; Blu-tak can be used to keep it closed.
With just some of the devices, a metal part may become detached. Metal to plastic glue fixes this.
If required, we replace the device for free.
In sound-mode, using the Device can be embarrassing!
Extra care is needed when using it in certain 'quiet' places such as meditation centres and churches.
The Device switches itself off when not held and not in contact with conductive surfaces, there is no On-Off button.
This makes carrying it around tricky. In your pocket or handbag, for example, it may start working unexpectedly.