Wireless Temperature Monitoring Device

I wasn't aware that restaurants now are using a wireless temperature monitoring device.  My family used to be involved in the restaurant business and we've never had this before.  We used to get this service from a temperature monitoring company who checks the restaurant and the food storage from time to time.  I only heard from a friend who owns Cafe Monaco that she uses this now.  Well, that's great because aside from saving money from hiring a company to do this for you, you can now keep track of your place's temperature any time.  I think even other establishments are using this device.