The software is incomplete and does not allow important functions. No support is provided the 540 and it does not work as the owner's manual states. The Internet is filtered to hide all Edge 540 problems. You cannot return the 540 to purchase the 840. Without touchscreen on the 540, the buttons work very poorly and are almost impossible to use. Garmin is selling a somewhat defective product and blocking any efforts to get support. Editing a Data Screen and Activity Profiles cannot be done on the Edge 540. Search for Edge 540 problems on Garmin Forums and the Internet and you will find many more reasns to nut purchase Edge 540.