Liftmaster 41a4373a Garage Door Openers Safety Sensors For garage door openers that currently have sensors installed 41A4373A sensors are compatible with LiftMaster and chamberlain brand from 1993 - late 1990's Each sensor has a green light and a bolt that runs right through the center of each sensor Designed to splice into your existing wires Includes 1-sending unit, 1-receiving unit, wire connectors and instructions - no brackets