Constant temperature and humidity test chamber can also be called temperature and humidity environment test chamber, is through the simulation of high temperature, low temperature, as well as temperature and humidity of the constant or alternating environment, electronic and electrical appliances, cell phone communications, instrumentation and vehicles, and other industries in the quality of the product testing of the test equipment. Temperature fast change, is a fast temperature change test box tube, it is faster than the constant temperature and humidity test box temperature change rate. Constant temperature and humidity test box does not have the function of sudden change, sudden change in temperature, is the cold thermal shock test box tube.