Confused about Booster - first time mom questions

[SoCalMommy]

I will check my Baby Bargains book, but it's 4 years old and I know products and laws change.hoping this board can give me a quick lesson....

DD is almost 4 yrs old but already 40 lbs and at least 42 inches tall. We have Britax MA70 in our cars, but the Grandparents car seats are different. One has the a First a Years True Fit (I am pretty sure that goes to 65lbs.) and the other is an Evenflo Tribute. It seems we hit the maximum weight and height for that one. i am guessing that we should look at a booster option for their car now instead of another convertible car seat, right?

Since that car seat is not used as often, they do not want to spend a lot. They like to take her places and sometimes longer drives during which she occasionally falls asleep in the car. Of course I want the safest option that we can use for a while.

I get the difference btwn a high back booster and backless. Given her stats and age, I was going to look for a high back, but I am confused beyond that....what is a harnessed vs. seatbelt, etc? Is that how it's installed or how the child is contained? Are there also height and weight limits on boosters? Does the car they drive matter at all?

What should I look for and how long are the high back boosters used? I have no idea and all the searches I have done on this board just confuse me more. Help! TIA

[Joolsplus2]

Look for a 'combination' seat or 'harnessed booster' or 'toddler booster'...basically you DO still want her harnessed (harnessing to age 5 and older is preferred for maximum safety, kids in the 4 range just don't fare as well using a car's seatbelt, generally there's a higher risk of head injury). So something that forward faces only with a harness for now, that becomes a 'belt positioning booster' later, and maybe even converts to a backless after that.
The good news is, there're lots of choices .
Scroll way down in this blog to see some top choices http://carseatblog.com/carseatblogco...ded-car-seats/
The faves around here range from the high dollar Frontier 90 to the basic Maestro. I was thinking the Evenflo Secure Kid for the comfort of it and the low price and ease of install (LATCH for a few more pounds, then a super easy seatbelt install, then it makes quite a nice booster with great head support). Or the Nautilus is the model that also converts to a backless later, it's not known to be comfy for sleeping, as it is very upright in most cars (tons of head flop...though maybe the Safety Surround version at Target is better, I don't know anyone who owns one to report on it for sleeping!)
Hope that helps a little!

[SoCalMommy]

Thank you Jools! This helps a ton!