Booster seats and harness-to-booster seats are designed to keep older children safe and comfortable as they transition out of car seats. Booster seats are intended for children who have outgrown their forward-facing car seats but are not yet tall enough to use the vehicle's seatbelt alone, typically between 4–10 years old and 40–100 pounds. Harness-to-booster seats offer a 5-point harness for younger kids and convert to a belt-positioning booster as they grow, making them ideal for extended use. Always check the manufacturer’s height and weight guidelines to ensure a proper fit.