Kimtech Pure W4 Critical Task Dry Wipers have a 100% polypropylene construction and are thermally bonded with no glues or binders. They are acid-, base- and solvent-resistant and feature straight, clean knife-cut edges to minimize lint. The wipers are double bagged with a case liner and are specifically designed for ISO Class 4 and higher cleanrooms. These wipers are ideal for use in the pharmaceutical, high tech, biotechnology and medical device industries. Additionally, the polypropylene used in the manufacture of Kimtech Pure W4 Dry Wipers meets the requirements set forth by the FDA for Olefin polymers (21 CFR 177.1520) used for food packaging/contact. (Please note, the FDA does not regulate wipers as food packaging).