Ginger, I don't think they're unsafe if used correctly, it's just that it's so easy to not fit them correctly. As far as why they are sold, I guess it all comes down to baby store profit But yes, you can buy one of those boosters (or there's a Hipod one that's highly rated too) without the harness. I got the Infa one for $125. Although check out how the seatbelt fits on the MR you've already got - if you're happy with the anti-submarining clip and the "fit" of the seatbelt around his neck, you would be fine to use it with the seatbelt as Olive suggested. The manual should show you how to convert it to booster mode.