I use the Specialized Propero 3 with ANGi. It tracks your position via GPS and sends a link to my contacts on start and stop of my ride. It also has crash detection and will notify all my emergency contacts with GPS location of where I am. It it a good piece of mind for me as I have spoken to people who said they have crashed on the trail somewhere and no one knows where they are or even that they were hurt. So I looked at the marked and found the Specialized with ANGi for my needs.