Chamberlain LiftMaster 312HM Universal Coaxial Receiver
Compatible with Security+ Rolling Code, Billion Code, and DIP switch technologies.
High Security mode: stores 15 Security+ remote/keypad codes.
Normal Security mode: stores 31 LiftMaster remote/keypad codes.
Powered by: 12V DC or 18-35V AC/DC (jumper selectable).
Includes: 8" external whip antenna.
For use with openers operating at 315MHz.