The M1XRFTWM two-way wireless transceivers allow an ELK-M1 or ELK-M1EZ8 control to accept Elk?s complete line of two-way wireless sensors. The ELK-M1XRFTWM has been optimized to provide superior signal reception and reliability in multi-transceiver applications.The ELK-M1XRFTW has been replaced by the ELK-M1XRFTWM. The ELK-M1XRFTWM performs all the functions of the ELK-M1XRFTW and is suitable for single or multiple transceiver installations.Do NOT mix ELK-M1XRFTW and ELK-M1XRFTWM transceivers in a single M1 installation.M1XRFTWProduct DetailsFeatures:Allows up to 144 individual wireless zones (sensors/points)Operates from the 4 wire RS-485 Data BusUp to 4 M1XRFTWM transceivers may be connected to a single M1 or M1EZ8 control for redundancy and greater coverageFlash memory for firmware updatesSpecificationsOperating Frequency: 902 Mhz to 928 MhzSensitivity: >105 dbmOperating Temperature: 0 to +120 degrees FOperating Voltage: 12 Volts D.C.Current Draw: 25mA receiving, 85mA transmittingHousing Dimensions: 6.75? x 4.69? x 1.13?