3. Two lower anchorages
Child restraint anchorage systems should have two lower anchorages.
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Child Restraint Anchorage Systems is something which establishes strength, location and accessibility requirements for lower anchor bars and top tether anchors used for securing a child restraint in a motor vehicle.
The purpose of this standard is to reduce the likelihood of anchorage systems failure, and to increase the likelihood that child restraints are properly protected and thus fully realize their potential potential in vehicles.
Source: nhtsa.gov