A "harnessed seat" refers to a specialized chair or harness that is designed to keep someone securely fastened in place, preventing them from getting hurt or moving around too much. Full definition
A 5 point harness seat belt system is essentially the must for safety and stability for both you and kids. (omgstroller.com)
First, it is an extended 5 point forward facing harness seat for children up to 65 pounds that features an easy to install system with a lock off buckle for easy secure installation. (pocketyourdollars.com)
A five or at least three - point harness seat belt is necessary to keep your baby safe during jogging. (getyourreview.com)