Zep Big Z Heavy Duty Tractor Trailer Wash is a powerful, liquid, alkaline trailer wash for use on unpainted aluminum, fiberglass, and painted aluminum trailers. This non-acidic, phosphate-free formula effectively removes dirt and grime without etching or frosting glass. Ideal for industrial and institutional use, it ensures thorough cleaning with a concentrated blend of heavy-duty detergents, emulsifiers, alkaline builders, water softeners and inhibitors.