Inside the clean zone materials need to be transferred from one grade of room to other. This demands the air to be restricted for transferring from one to other and prevent cross contamination.Pass boxes are made to solve this issue. These are airtight metal enclosures with doors ,three doors configuration having electromagnetic or mechanical interlocking to prevent all doors opening at the same time. U.v.light also provided for killing microrganism.standard size: 1’ x 1’ x 1’ , 2’ x 2’ x 2’. Other sizes can be made as per order.