The Model D-24A Normally Closed Wall-mount Transmitter has a normally closed input circuit that operates in conjunction with an externally mounted normally closed magnetic or mechanical contact, window foil, or security screens. When the external circuit opens for at least one-second, the transmitter automatically transmits a two-second digitally coded signal to a companion standard digital receiver. Pressing the test pushbutton on the front of the transmitter will also cause the transmitter to send a signal. Each transmission causes the red LED indicator on the front of the transmitter to light, showing that the transmitter is sending a signal and that the battery is in good condition.

General Specifications Encoding Techniques: 8-position DIP switch provided for code setting) RF Carrier Frequency: 303.875 MHz Current Consumption: 12 mA DC transmitting Power: 9 VDC NEDA battery (supplied) Operating Temperature Range: Battery limited Dimensions: 2.4 in W x 4.7 in H x 0.9 in D (62 x 120 x 23 mm)	Features Slimline case design Test/operate switch Test/operate LED 2-second transmission Standard digital format: 256 selectable codes One N/C input loop circuit Loop input screw terminals Powered by one 9-volt battery (included)