The phrase "chair harness" refers to a device or system that helps secure someone to a chair for safety reasons. It is often used to keep individuals with limited mobility or balance from falling out of their chairs. Full definition
One thing to bear in mind is that the high chair harness is not included and must be bought separately. (mombible.com)
It also has an integrated chair harness to transform an adult chair into a safe seat for your growing baby to. (babycarrierreviewguide.com)
Recommended for babies and toddlers aged 6 - 30 months, our lightweight, compact and versatile chair harness anchors your child safely and comfortably in almost any dining chair. (totseat.com)