It consists of a pair of contacts on ferrous metal reeds in a hermetically sealed glass envelope.

The reed switch contains a pair (or more) of magnetizable, flexible, metal reeds whose end portions are separated by a small gap when the switch is open.

Instead of using piano strings, Bell and others were using a set of metal reeds like the ones in a harmonica, each tuned to vibrate at a different frequency.

This comprises a number of vibrating metal reeds, each one having a tuned vibration frequency like a tuning fork.

The Pianet's sound was piano-like, sharing sonic similarities to the Wurlitzer series of electric pianos as both relied on metal reeds and variable capacitance as their sound generation source.

The tuned reed system brought new sophistication, using metal reeds to resonate with the transmitted signal and operate one of a number of different relays.

Two thin metal reeds, mounted in a box inside the instrument panel, vibrated in response to a radio beam that was transmitted from the ground.

Some horns, like the Daboll trumpet, used vibrating plates or metal reeds, a similar principle to a modern electric car horn.

The leather is saturated with a viscous silicone oil to adhere to and pluck metal reeds.

Bell also thought that multiple metal reeds tuned to different frequencies like a harp would be able to convert the undulating currents back into sound.