The Model ACT-22B from Linear is a 3-Channel Block Coded Key Ring Transmitter is designed for use with Linear's access control products. Pressing the transmitter's left or right front button sends channel 1-or 2. Pressing both buttons sends channel 3. Lithium batteries with a 5-Year service life are included and the transmitter is supplied with a quick-Disconnect key ring. A unique 10-Second time-out feature prevents the system from being shut down by a single transmitter transmitting continuously.