Lexus 2012 RX450h Owner's Manual page 176

1-8. Safety information
Forward facing  Convertible seat
Booster seat
Selecting an appropriate child restraint system
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Use a child restraint system appropriate for the child until the child becomes
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large enough to properly wear the vehicle' s seat belt.
If the child is too large for a child restraint system, sit the child on a rear seat and
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use the vehicle's seat belt. (P. 111)
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