The GET one I had (and probably all GPS ones) let you set splits. Mine would flash a green or Red LED as you passed the split and tell you how much up/down you were on that split (to your best lap). It was nice I keep seeing that green LED in the bottom of your vision as you worked your way through the first session.

With splits it also may give you the lap time that you could have done by combining the three splits.

I don't use this as I think I might already know I could do better. I do like gps for ease of setup and other peoples beacons not interfering.

M