Act-34B block coded megacode remote The Model ACT-34B 4-Channel Block Coded Key Ring Transmitter is designed for use with Linear's access control products. The Model ACT-34B is a four-channel device supplied with a quick-disconnect key ring. Also included are lithium batteries with a five-year service life. A unique 10-second time-out feature prevents the system from being shut down by a single transmitter transmitting continuously. Features: Compatible with Linear access receivers and controllers that are weigand block coded type Supplied with quick-disconnect key ring. RF frequency: 318 MHz.