The new securityProbe 5E has all the functionality of the previous generation secuurityProbe, but is faster and expandable. This is what the 4 RJ-45 expansion ports on the front of the unit are for. The new SEC 5E is now faster with a 520 MHz CPU and has more memory at 128MB. It also has an on board SD card slot that comes with standard with a 2GB SD card. The new unit now has two USB ports in place of the serial port. You can use a serial to USB converter and will still be able to use the same USB and serial modems. You can use any modem that worked on the previous generation securityProbe.