Liftmaster 355LM Garage Door Receiver 315Mhz Conversion Kit 355LM unit is also a CONVERSION KIT utilizing 315MHz security + technology. Security+ technology upgrade or replacement receive The code between the remote and receiver changes with each use for extra security Over 100 billion possible codes makes it impossible to duplicate the frequency. Accepts multiple remote controls utilizing up to 8 functions, and one Security+ keyless entry.