Linear GT-31 3-Channel Genie Compatible Key Ring Transmitter GT-31 3-channel Genie Compatible Key Ring Transmitter 3 buttons and 3 channels to operate three independent gate, garage, and/or other access operations. Test/operate LED. Black case color. Molded-in hole to accept keychain or keyring. Anti-code-theft, rolling code technology. Quick-disconnect keyring supplied. Codes: randomly selected from over 4 billion codes with each button press. Frequency: 390 MHz.