This is a vintage Guyatone footswitch designed for controlling reverb on an amplifier. The footswitch is specifically made for Guyatone amplifiers and provides a convenient way to activate or deactivate the reverb effect while playing. It is a type of switch that allows guitarists to easily toggle the reverb on or off without having to reach for the amplifier controls. This footswitch is a sought-after accessory for musicians looking to enhance their reverb capabilities during performances or recording sessions.