The Model ACT-34DHC 4-Channel Factory Block Coded Key Ring TRANS PROX Transmitter & 26-bit HID Compatible Proximity Tag is designed for use with Linear’s access control products. The Model ACT-34DHC 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.