The Linear 1-channel keychain transmitter in black color is perfect for all Linear access receivers controllers. This transmitter has a quick-disconnect key ring for convenience. The Linear ACT-31B 1-channel keychain transmitter has 10 sec time-out feature that resist the system from being turn off by a single transmitter. It features MegaCode format and eliminates code duplication. It prevents unauthorized access to the system as the receiver learns each specific code. This transmitter is perfect for garage door openers and gate operators. It has 1 button remote control that is useful for one door or gate. This block coded transmitter is factory programmed for a sequential series of transmitter ID codes.