Although you can use convertible car seats for infants, infant-only car seats are the best fit for small infants. Convertible car seats can be used in the rear-facing position, and then, when your child is big enough, they can be turned around to face forward. Combination seats allow you to use the car seat with the harness. After that you can use it with the your car’s seat belts as a belt-positioning booster. High-back boosters, which provide better protection, are for cars with low back seats and no headrests. Backless boosters are for cars with backseat headrests.
In 2003 after the breakup of Columbia during re-entry, the Columbia Accident Investigation Board conducted tests at Southwest Research Institute , which used an air gun to shoot foam blocks of similar size, mass and speed to that which struck Columbia at a test structure which mechanically replicated the orbiter wing leading edge. They removed a section of fiberglass leading edge from Enterprise 's wing to perform analysis of the material and attached it to the test structure, then shot a foam block at it.  While the leading edge was not broken as a result of the test, which took place on May 29, 2003, the impact was enough to permanently deform a seal and leave a thin gap 22 inches (56 cm) long.    Since the strength of the reinforced carbon–carbon (RCC) on Columbia is "substantially weaker and less flexible" than the test section from Enterprise , this result suggested that the RCC would have been shattered.  A section of RCC leading edge from Discovery was tested on June 6, to determine the effects of the foam on a similarly aged leading edge, resulting in a three-inch ( cm) crack on panel 6 and cracking on a "T"-shaped seal between panels 6 and 7.   On July 7, using a leading edge from Atlantis and focused on panel 8 with refined parameters stemming from the Columbia accident investigation, a second test created a ragged hole approximately 16 by 16 in (41 by 41 cm) in the RCC structure.   The tests clearly demonstrated that a foam impact of the type Columbia sustained could seriously breach the protective RCC panels on the wing leading edge.