This endorsement is required to haul any liquid or gaseous materials in a tank or tanks having a capacity of 1,000 gallons or more that is either permanently or temporarily attached to the vehicle or chassis. To receive this endorsement, applicants must pass a test. The test consists of 20 multiple choice questions. Each question has three possible answer choices. To pass, the applicant must answer at least 16 questions correctly. Test questions come from the Oklahoma Commercial Driver License Manual. Questions come from chapters covering: Driving Safely, Tank Vehicles, Hazardous Materials and Combination Vehicles. The Tank endorsement can be used with the Class A, B or C CDL.