Abstract: A transport carrier for transporting x-ray masks, wafers and the like, from an ultra-clean environment to another through a lesser clean environment. The apparatus includes a box that is sealed from the outside by an access door, one or more fans, at least one air filter, rechargeable batteries or a continuous voltage supply for powering the fans. It also includes a damper mechanism for maintaining a positive air pressure when the access door opens. The damper also secures recirculating air inside the box when the door closes. The recirculating air is continuously cleaned at a rate of 2,000 times/minute. The air filter is placed horizontally, preferably, over a frame facing the product to be transported to ensure a continuous smooth, laminar flow.