I have a Genie garage door opener, and they sell a tiny transmitter that's about 2-1/2" long, an inch wide, and a 1/2" deep. With some good double-back foam tape, I've mounted this garage door opener on that unused blank plastic cover! Works slick ... and a LOT cheaper than the BMW arm-rest universal garage door opener that JonM sells (although not as "cool"). FYI