CDL Prep is the best way to prepare for the Commercial Drivers License General Knowledge, and various endorsement exams. CDL Prep contains questions on the following topics: General Commercial, Air Brakes, Combinations, Hazmat, Passenger, Tanks, School Bus, and Doubles/Triples. Features: 1. Over 500 questions to practice with. 2. Exam Mode - 60 minutes to answer 50 randomly chosen questions, or 40 minutes to answer 20 to 30 questions on endorsement topics. At the end, review your score and any incorrect answers. 3. Practice Mode - Answer questions and receive instant feedback if you answered incorrectly. 4. Answer Randomization - Answers to questions will not always be in the same position. 5. Performance tracking - Review your performance on every question. Red = You have an average score less than 70%, Orange = You have an average score between 70-89%, Green = You have an average score of 90% and above. Please send any feedback or request to: [email protected]. Thank you and good luck on your exams!