Forward-facing safety seat: From at least 1 year old and over 20 pounds to around 4 years old and 40-65 pounds.
Booster: From around 4 years old and 40-65 pounds to 8-12 years old and 80-100 pounds (depending on the seat), and at least 4'9".
1. The harness straps should be in slots at or above your child's shoulders, and the top of the clip should be at armpit level. Be sure the straps are snug.
2. Unlike with convertible seats, all harness slots in combination seats have the extra reinforcement necessary to keep the harness secure forward-facing, so just choose the one that fits best.
3. Use the harness until your child is ready for a booster seat (see checklist below). Then remove the harness and use the seat with your vehicle's lap-and-shoulder belt.
Ready for a booster?
Yes, if any of these boxes are checked:
Your child's ears are above the top of the seat.
Her shoulders are above the top harness slots of the seat.
She has reached the maximum forward-facing weight limit.
*Some combination seats can also be used rear-facing for babies.