Pass box(also pass through box) is an auxiliary device for clean room. It is mainly used for transferring of small items between clean areas of different classes of cleanliness, also between clean area and non-clean area, to reduce the number of times the clean room is opened, and to reduce the possibility of polluting the clean room to a minimum level. The pass box is made of stainless steel and is plain and smooth. The double doors are interlocked to each other to effectively prevent air exchange and cross-contamination. They are equipped with electronic or mechanical interlocking devices and ultraviolet germicidal lamps. Dynamic pass box can remain self-cleaning, it also has the function as air locks to prevent air convection between different clean rooms.