Polyvinyl butyral (or PVB) is a resin mostly used for applications that require strong binding, optical clarity, adhesion to many surfaces, toughness and flexibility. It is prepared from polyvinyl alcohol by reaction with butyraldehyde. The major application is laminated safety glass for automobile windshields. Tradenames for PVB-films include Saflex, GlasNovations, Butacite, WINLITE, S-Lec, Trosifol and EVERLAM.