This one is even cooler. It connects to your phone (via Bluetooth I assume) and automatically sends data to it. So you don't even have to remember to scan the sensor, just check your blood sugar on your phone. And the app has alarms for when things start getting to high or to low.
A big difference between these sensors and poking your fingers is that when you poke your fingers all you get is a snapshot of what your blood sugar is in that moment. When you scan the sensor it transfers all the data since your last scan and displays it in a graph immediately so you get to see the mountainous spikes from eating those mashed potatoes. I've mostly stopped eating some foods because they wreck my blood sugar but I wouldn't have known that was happening w/o the sensor. And my smart phone.