What is the most important factor in the oven thermometer precision?

With the improvement of people's living standard, for the food quality request more and more is also high. Especially in all kinds of dessert, so the oven almost became the standard of modern family. Generally the somebody else will deserve a oven thermometer as follows. Models: OT300 oven with circular thermometer type: circular thermometer with stent materials: the SS304 pan/aluminum black circles on the cover surface diameter: 75 mm temperature range: 50 - 300 c ( Can be customized) Accuracy: & plusmn; Table: 2% glass protection grade: IP55 ( Dust, water) This is a plastic table, SS304 enclosure, with the base support of the oven thermometer, reading intuitive, easy to use, cleaning is very convenient. We use it to measure the temperature of the oven, so that we can make a delicious dessert. So for the oven thermometer accuracy requirement is very high, because if the temperature is not accurate, make food taste will also be discounted. So what is the most important factor in the oven thermometer precision? Is the middle of the riveting panel spiral heat element, must let the temperature sensing element and absolute vertical panel, otherwise the measured temperature is not allowed.