Buy Linear ACT31B keychain Block Coded Original Equipment Garage Door Opener (p/n: ACT31B keychain Block Coded) Linear act-31b block coded remote Linear&39;s ACT-31B offers a cost effective means of incorporating the security and convenience of block coded transmitters into nearly any access control application. This model is sequentially precoded at the factory with unique ID codes, as well as facility codes. This coding combination represents the same level of security as a traditional Wiegand card. The ACT-31B transmitter is small enough to be carried on a key ring in a pocket or purse. The ACT-31B is a single-channel model used where only one remote control function is needed, such as an entrance gate that utilizes a free exit loop. Programming ACT-31B transmitter into system memory is as simple as entering the first and last number of the coding block into the controller. Depending upon which type of controller, transmitters can be enrolled either by user-friendly programming software or manually at the controller keypad.