Characteristic as follows: 1.It has reasonable receive band width, strong anti-jamming, the suppress is up to -50dbm for 944Mhz. 2.It has excellent ability of suppress assemble or scatter radiation, easy pass kinds of instrument. 3.Due to excellent shield ,it can adapt to kinds of installing environment, and it has nicer consistency and cabinet shape. 4.It has ability to restrain the radiation, can worked with several pieces module (one piece transmit module and several pieces receive module ), and have no interference to each other, and do not influence the receive distance. 5.Adopting the SAW, the capability is immobile, and the temperature range is wide;saving electricity, when power is 5V, wastage of electricity is approximately 4.8mA. 6.Frequency range is 250-450 MHz, easy to adjust. 7.Use microprocessor directly link, transmiting speed is up to 4.8kbps; it has good competitive price.