[header] How to buy a convertible car seat [title] Research the safety features of different convertible car seats you are considering. [substeps] Make sure the models you look at have 5-point harnesses, as this ensures a better fit which is safer for the child. Check the straps to make sure they are wide and do not easily twist. 
Twisted straps reduce the area of strap that would restrain a child during a crash, diminishing the seat's effectiveness. Look for convertible car seats that have front harness adjustment.