Corrugated plastic or corriboard – also known under the trade names of Biplex, Cartonplast, Polyflute, Coroplast, FlutePlast, IntePro, Proplex, Correx, Twinplast, Corriflute and Corflute – refers to a wide range of extruded twin-wall plastic-sheet products produced from high-impact polypropylene resin with a similar make-up to corrugated fiberboard. It is a light-weight tough material which can easily be cut with a utility knife. Manufacturers typically offer a wide variety of colors, thicknesses, and weight. Polycarbonate sheet is sometimes referred to as twinwall plastic. Chemically, the sheet is inert, with a neutral pH factor. At regular temperatures most oils, solvents and water have no effect, allowing it to perform under adverse weather conditions or as a product component exposed to harsh chemicals. Standard sheets can be modified with additives, which are melt-blended into the sheet to meet specific needs of the end-user.