By Dexcom. Actual product size shown. Selling the Stelo glucose monitors for $40 for one sensor. Each sensor lasts for 15 days. It is basically a patch that goes on your arm and monitors via and app, gives updates every 15 mins so you know if your blood spikes or not. If you buy from dexcom there is a two sensor minimum so this is a good way to get a good idea in just 15 days and save money. I got extras bc I thought I’d need more time but 15 days is enough. I can also give you free glucose hacks on how to reduce through behavior if you buy a sensor from me.