Dynamic pass box is the self-cleaning transfer device in cleanrooms. Pass box function is to transfer items and to reduce the number of door openings in cleanroom. It's mainly installed between a cleanroom and a non-cleanroom, or between a high-level cleanroom and a low-level cleanroom. Dynamic pass box is normally used to transfer materials and goods between cleanrooms of different levels or between cleanroom and non-cleanroom. Besides UV light and an interlock system, dynamic pass box is equipped with a suction HEPA filter of around 0.3 microns.