What are the weight and height requirements for booster mode on the Tranzitions?

For high back booster mode, children should weigh 30-100 lb (14-45 kg) and be 38-57 inches (96-145 cm) tall, at least 3 years old. For backless booster mode, children should weigh 40-100 lb (18.1-45 kg) and be 43-57 inches (110.1-145 cm) tall, at least 4 years old. (Page 42)