Certainty

What good is FM technology if you can't be SURE that it works?

One disadvantage to previous FM systems was that the teacher received no confirmation that the FM system was functioning properly. Unfortunately, many of the students requiring FM systems were unable to confirm their functional status.
Amigo FM automatically confirms integrity and functionality using the easy-to-see LED light built into the child’s receiver.

The hearing-aid battery is functioningThe receiver is ON
The transmitter and receiver are working perfectly
The child is on the right channel