This is the motor control box for the Deluxe heat & massage chairs.  It is used on chairs that have the Deluxe systems that use our part #8218 and #8219 hand controls.  This is usually the problem if you have this style chair, and you are hearing a loud “click” from this box when you press the thumb switch on the hand control.  It will have one or two wires coming from the box, depending on the chair, and normally has a sticker on one of the cords that says “REL1011” or “REL1012”.