Sunshine Kids RadianXTSL

If you like the top-rated Sunshine Kids Radian65SL (*Est. $230) but need a seat with a higher weight limit, the Sunshine Kids RadianXTSL can keep a child front-facing in a five-point harness until he or she weighs 80 pounds or is 53 inches tall (or rear-facing from 5 to 45 pounds). The Sunshine Kids Radian80SL (*Est. $265) has the same height and weight limits, but the XTSL adds a height-adjustable headrest and deeper side-impact protection. The slightly less expensive Radian65SL gets the most recommendations; its weight limits are 5 to 40 pounds rear-facing and 65 pounds forward-facing.

All Radian seats get high marks for safety in reviews, with their stiff steel alloy frames and top tethers that work either rear- or forward-facing to keep the seat's head area from jolting around in a crash, helping to prevent head injuries. The Radian seats also fold up for easier carrying ("we can hear parents of kids in carpools applauding from miles around," say testers in "Baby Bargains," though testers at Babble.com say this is more of an idea than a practicality since the seat weighs 24 pounds), and their slim design allows three to fit in one backseat. However, in a rear-facing position, these tall seats can eat up all of the front passenger's legroom in some cars. The Combi Coccoro (*Est. $195) is much smaller and lighter and fits three across, although it doesn't fold up and has far lower height and weight limits than the Radian seats. Reviews say both the Coccoro and RadianXTSL can be hard to install rear-facing. If you don't need to fit three across and don't need a particularly portable seat, reviews recommend the Britax Marathon Classic (*Est. $270); it too has high height and weight limits and advanced safety features, and reviews say it's easier to install.

Most reviews cover the Sunshine Kids Radian65, but the Radian65SL's only difference is a "Super Latch" connector that makes the LATCH system strong enough to use up to the full weight limit of the seat (rather than strapping the seat in with the seatbelt at high weight limits).