1.Material:Stainless steel#201 housing&back cover、、glass lens、aluminum dial &pointer.2.Dimension:Dia 130*Thickness18mm.3.Technical data:Temperature measuring range ....-30 to +50 ¡æ.Temperature tolerance .....¡À1% (from +10 to +30 ¡æ); ¡À2% (further ranges). Humidity measurement range .....20 to 100%.Humidity tolerance......¡À5% (from20 to 100%) ;4.Do not use it beyond temperature & humidity range.5.Features:Free battery、energy saving.6.Regarding calibration:All products have pass strict inspection and calibrating before go out from factory、remove the product from packing box and placed in 1~2 hours it will display correct datas; but sometimes during transportation shock may leads to few products in wrong datas、There are two holes in the product back for adjust. to adjust the temperature and hygrometer you compare the numbers with a correctly functioning reference instrument.