Getting ready to switch my boys over to a booster car seat. They will be 4 in september and we have another one on the way. I was going to get the backless booster seat, but now there are a ton that have backs to them. The backless is much cheaper, so I was just wondering what the difference is. Is backless for an older child?

I have not had too much time to look up all the info on this and figured I would come to the experts. Thanks!