Question: what are the requirements for a backless booster seat?
Answer: Children who weigh at least 18 kg (40 pounds) and who are at least 4 years old with the maturity to sit correctly should use a booster seat once they have outgrown their 5-point harness. Children should continue to use a booster seat until they are 145 cm (4 feet 9 inches) tall and fit the adult seat belt correctly.