Transmitter Solutions Firefly 315LMD21K Remote Liftmaster Compatible Brand: Transmitter Solutions Dimensions: The Transmitter Solutions Firefly Transmitter is very small Key chain style wireless transmitter operating at 315 MHz. The Firefly achieves its small size by using state-of-the-art surface mount components. It has been designed for use with and is compatible with dip switch receivers operating at a 315 frequency including all LiftMaster 9-dip switch digital receivers. Type: Garage Door Openers