Linear dxs-21 The Model DXS-21 Supervised 2-Button, 1-Channel Handheld Transmitter is a supervised, digitally coded radio transmitter designed for use with Linear's DX and DXS Format receivers. Pressing a button on the transmitter sends a digitally coded wireless signal to its companion receiver. To send a complete signal, press the transmitter button for a minimum of 2 seconds. The top button can be hidden with the top button cover supplied. The DXS-21 is a two-button, one-code transmitter. Pressing either the round button on the transmitter's front, or the small button on the transmitter's top will send the same signal. The digital DXS code format features over a million possible codes. The DXS transmitters are precoded at the factory to unique codes, so no field coding is required and can send a signal for up to 10 seconds per activation. The DXS-21 is supervised for low battery and sends hourly status reports. Some receivers are able to use these signals, others are not. Receivers must be programmed to the transmitter code before system testing and operation. Refer to the receiver's instructions for details on operation and programming. Each DXS-21 is powered by two self-contained type 2032 3-volt lithium batteries (included). When the batteries voltage gets low, a low battery report is sent with any alarm or status report to notify the receiver. The red LED will blink when the transmitter is activated with low batteries. A removable pocket clip and belt clip are provided for each transmitter. Either can be attached to the back of the transmitter allowing the unit to be clipped to shirt pocket or slid onto a belt. Complete RF supervision Alarm, supervisory, and low battery transmissions Unique ""Extra"" top button High visibility operate LED Two type 2032 lithium batteries supplied Pocket and belt clip supplied DXS format RF frequency: 315 MHz Specifications Dimensions: 1.6 in W x 4.2 in H x 0.8 in D (41 x 107 x 20 mm) Power: Two 3V DL-2032 lithium batteries (supplied) Linear dxs-21 transmitter Current Consumption: Standby: 1 µA Alarm: 8 mA average while transmitting Battery Life: Five years typical Measured Range: 1,500 feet minimum, open air (four quadrant test into DXSR-1504) Channels: 1 channel - top or front Operating Frequency: 315 MHz