It's a Dexcom7 (
http://www.dexcom.com/html/dexcom_products.html). My health insurance (United Healthcare) decided about a month ago that they were going to start paying for them (after deductibles, etc...), so keep checking back with your insurance company. The sensors cost about 260/month (I pay 26 after insurance), and each one has it's own built-in inserter. The tape that holds these things on is fantastic. I wish that my silhouette infusion sets used the same adhesive. The wireless transmitter snaps into the infusion set and the entire thing isn't much bigger than my Minimed silhouette.
I have to check my blood sugar every 12 hours to calibrate the dexcom, and for at least 7 days, the calibration reading was within about 10 points of the dexcom. Some people wear the sensor longer than 7 days, but mine starts to get flaky readings after that.
I put the meter on the bedside table at night (the wireless range is about 5 feet). If my blood sugar goes above 200 or below 70 it beeps/vibrates. That range is configurable. If my bs gets below 55 it beeps VERY loudly until I press a button. That level is not configurable. Prior to using the dexcom, my bedtime and breakfast readings were right around 100. It wasn't until I started using the dexcom that I discovered I was dropping down into the 40s at night and then bouncing back by breakfast.
Do a search on Youtube for dexcom, and you will see some videos of how to insert the device.