PeachSuite Hotel Supply, Bloomingdale's and Kitchen Kapers all carry oven calibration thermometers. The purpose of these devices is to measure any discrepancy between the desired temperature inside an oven and the actual heating that the oven provides.
Models such as the OXO oven calibration thermometer feature frosted glass in the back, allowing the oven light to illuminate the dial from the rear and shine all the way through. They have a clip permitting the user to hang it from one of the oven racks or set it atop one of the racks. The clip holds the thermometer in place so the user can move food in and out of the oven without having to worry about knocking the thermometer off. The thermometer also offers both Fahrenheit and Celsius scales for increased versatility and convenience.
Quite a few of the oven calibration thermometers available for sale are made of stainless steel to provide durability. An important feature to look for is numbers that are large enough to read easily through the door of the oven. While warranty guarantees vary by manufacturer, OXO products are guaranteed by the manufacturer. OXO permits return of any defective products for either a refund or replacement.