LiftMaster CPI-EI Sensing Edge Interface 041A2818 is a limit switch

041A2818 is a limit switch and drive gear replacement kit that includes

Liftmaster 50-19503 Push to Open Bracket Kit for LA400

These go inside the C-Channel rail for certain Genie screw drive model garage door openers

Receiver accepts up to (4) transmitters

LiftMaster CPI-EI Sensing Edge Interface 041A2818 is a limit switchDesigned to provide advanced safety and security to the door system in commercial environments. This device is intended for use with LiftMaster Logic Commercial door operators and compatible with 4 wire monitored sensing edges. This is a stand alone reversing system and is not intend to be used in conjunction with any additional entrapment protection devices. A junction box, not provided, is recommend to protect exposed wiring. Compatible with Logic