A wide variety of sizes are available for pass box and they make it possible for passing materials & parts in or out of a clear room without contaminating the controlled environment. To maintain the clean room or critical area at highly cleanliness level by eliminating unnecessary personnel pass in and out. A mechanical or electrical door interlocking system prevents cross-contamination by making it impossible to open both of front & rear doors at the same time. Or, trying to open a door as long as the opposed facing door either is open or ajar. Size:w680*d500*h620mm W800*d800*h170mm