Laminated Center Sealed Valve Bag provides a rigid sift resistant valve opening. The film is typically 1.5mil HDPE laminated to a stiff backing. The backing is generally 33lb liner board. Polyethylene is more flexible than paper and is more effective at trapping product in the bag than a paper tube insert. It is one of the most common and in demand bags that businesses use to package their products. After filling, this valve then is closed, sealing the bag. One advantage of using Laminated Center Sealed Valve Bag is that they do not require a bag sewing machine or bag sealer to close the bag.