We purchased 7 of these for our children starting at age 3 between our cars and the in-laws cars and have owned them for 3 years now. We have successfully installed them in several different vehicles (Cadilac DTS, Chevy Malibu, Chevy Uplander, Chevy Traverse, Chevy Silverado, Buick Enclave, Buick Rainer) all with latch. Our daughter (who has also had brain surgery) is 5 and 40lb still being harnessed, we recently stopped using the latch on hers and are using the seat belt install. We were able to keep our son harnessed until he was six and then he used a seat belt until he was 7.5, 63lb and 52 inches we put him in the bottom only booster. It did not however work in an Chevy Traverse or Buick Enclave bucket second row seat. We got the affix backless booster for those. It had a smaller footprint so it was easier to buckle himself. The cup holder is great, the cubbies are nice. The covers are easy enough to take off and wash. We have no complaints. We recommend them to everyone.