Analog switches are a solid state alternative to relays, when you want a smaller, lower-power technology that won't wear out mechanically. As the name implies, you can use an analog switch chip to select between two analog signals, much like a mechanical switch. These chips tend to be tiny surface mount parts, so the Adafruit STEMMA Analog SPDT Switch lets anyone use the MAX4544 SPDT analog switch for signals up to 12V, without fiddly soldering.