The Model DXT-41 1-Button, 1-Channel Key Ring Transmitter is a battery powered, portable, miniature transmitter designed for use with Linear`s DX Format receivers. Each transmitter can be used in a limitless number of wireless remote control applications. Pressing the transmitter button sends a digitally coded wireless signal to its companion receiver. The transmitter button has a positive click feel. The digital DX code format features over a million possible codes. The DX transmitters are precoded at the factory to unique codes, so no field coding is required. Transmitters can send a signal for up to 10 seconds with each button activation. The DXT-41 is a one-button, one-code transmitter. Pressing the button sends the transmitter`s code to the receiver. Press the button for a minimum of two seconds to insure receiver activation. The DXT-41 is powered from two 3-Volt Type 1620 lithium batteries with an expected battery life of up to 5 years. When the transmitter`s range decreases, or stops functioning, replace the batteries. A detachable key ring is provided with each transmitter. ** Specifications subject to change without notice.