BSS AC-5S-WHT-US Analog Wall Plate Controller with 5 Sources (White)The Soundweb Contrio AC 5S is a simple analog wall controllers designed for use with BSS Audio Soundweb London devices. The AC 5S is designed to connect to General Purpose Inputs (GPI) (also known as "Control Inputs") found on Soundweb London devices. Most Soundweb London devices contain 12 GPI. The Soundweb London BLU GPX contains 36 GPI. The AC 5S contains a single five position resistor ladder which is useful for source selection or preset recall.